text:
List of current heads of state and government
From Wikipedia, the free encyclopedia
Jump to: navigation, search
"World leaders" redirects here. For the CIA-published public domain directory, see World Leaders.
See also: List of state leaders in the 21st century
This is a list of current heads of state and heads of government. In some cases, mainly in presidential systems, there is only one leader being both head of state and head of government. In other cases, mainly in semi-presidential and parliamentary systems, the head of state and the head of government are different people. In semi-presidential and parliamentary systems, the head of government role (i.e. executive branch) is fulfilled by both the listed head of government and the head of state.
The list includes the names of recently elected or appointed heads of state and government who will take office on an appointed date, as presidents-elect and prime ministers-designate, and those leading a government in exile if internationally recognised.
Contents
[hide]
1 Member and observer states of the United Nations
2 Other states
3 Other governments
4 Other entities
5 See also
6 Notes
7 External links
Member and observer states of the United Nations
Legend:
Yellow highlighted cells indicate state leaders whose constitutionally interpreted positions (e.g. de jure) individually administer the governmental executive, legislature
Blue highlighted cells distinguish heads of state or party leaders chiefly regarded as exercising (e.g. de facto) further systemic influence, authority within their system of government
Names in small font generally denote acting, transitional, temporary leaders, or representatives. Other notes and exceptions are provided at § Notes.
State
Head of state
Head of government
Afghanistan
President – Ashraf Ghani[α] Chief Executive – Abdullah Abdullah
Albania
President – Ilir Meta Prime Minister – Edi Rama
Algeria
President – Abdelaziz Bouteflika Prime Minister – Ahmed Ouyahia
Andorra
Episcopal Co-Prince – Joan Enric Vives Sicília
Co-Prince's Representative – Josep Maria Mauri
French Co-Prince – Emmanuel Macron[β]
Co-Prince's Representative – Patrick Strzoda Head of Government – Antoni Martí
Angola
President – João Lourenço
Antigua and Barbuda
Queen – Elizabeth II[γ]
Governor-General – Sir Rodney Williams Prime Minister – Gaston Browne
Argentina
President – Mauricio Macri
Armenia
President – Armen Sarkissian Prime Minister – Serzh Sargsyan
Australia
Queen – Elizabeth II[γ]
Governor-General – Sir Peter Cosgrove Prime Minister – Malcolm Turnbull
Austria
Federal President – Alexander Van der Bellen Federal Chancellor – Sebastian Kurz
Azerbaijan
President – Ilham Aliyev Prime Minister – Artur Rasizade
Bahamas, The
Queen – Elizabeth II[γ]
Governor-General – Dame Marguerite Pindling Prime Minister – Hubert Minnis
Bahrain
King – Sheikh Hamad bin Isa Al Khalifa Prime Minister – Prince Khalifa bin Salman Al Khalifa
Bangladesh
President – Abdul Hamid Prime Minister – Sheikh Hasina
Barbados
Queen – Elizabeth II[γ]
Governor-General – Dame Sandra Mason Prime Minister – Freundel Stuart
Belarus
President – Alexander Lukashenko Prime Minister – Andrei Kobyakov
Belgium
King – Philippe Prime Minister – Charles Michel
Belize
Queen – Elizabeth II[γ]
Governor-General – Sir Colville Young Prime Minister – Dean Barrow
Benin
President – Patrice Talon
Bhutan
King – Jigme Khesar Namgyel Wangchuck Prime Minister – Tshering Tobgay
Bolivia
President – Evo Morales
Bosnia and Herzegovina
High Representative – Valentin Inzko
Presidency[δ]
Chairman of the Council of Ministers – Denis Zvizdić
Bakir Izetbegović (as Chairman)
Dragan Čović (as Member)
Mladen Ivanić (as Member)
Botswana
President – Mokgweetsi Masisi
Brazil
President – Michel Temer[ε]
Brunei
Sultan and Prime Minister – Hassanal Bolkiah
Bulgaria
President – Rumen Radev Prime Minister – Boyko Borisov
Burkina Faso
President – Roch Marc Christian Kaboré Prime Minister – Paul Kaba Thieba
Burundi
President – Pierre Nkurunziza
Cambodia
King – Norodom Sihamoni Prime Minister – Hun Sen
Cameroon
President – Paul Biya[α] Prime Minister – Philémon Yang
Canada
Queen – Elizabeth II[γ]
Governor General – Julie Payette Prime Minister – Justin Trudeau
Cape Verde
President – Jorge Carlos Fonseca Prime Minister – Ulisses Correia e Silva
Central African Republic
President – Faustin-Archange Touadéra[α] Prime Minister – Simplice Sarandji
Chad
President – Idriss Déby[α] Prime Minister – Albert Pahimi Padacké
Chile
President – Sebastián Piñera
China
General Secretary of the Communist Party – Xi Jinping
President – Xi Jinping Premier of the State Council – Li Keqiang
Colombia
President – Juan Manuel Santos
Comoros
President – Azali Assoumani
Congo, Democratic Republic of the
President – Joseph Kabila Prime Minister – Bruno Tshibala
Congo, Republic of the
President – Denis Sassou Nguesso Prime Minister – Clément Mouamba
Costa Rica
President – Luis Guillermo Solís
President-elect – Carlos Alvarado Quesada
Croatia
President – Kolinda Grabar-Kitarović Prime Minister – Andrej Plenković
Cuba
First Secretary of the Communist Party – Raúl Castro
President of the Council of State and President of the Council of Ministers – Miguel Díaz-Canel Bermúdez
Cyprus
President – Nicos Anastasiades
Czech Republic
President – Miloš Zeman Prime Minister – Andrej Babiš
Denmark
Queen – Margrethe II Prime Minister – Lars Løkke Rasmussen
Djibouti
President – Ismaïl Omar Guelleh[α] Prime Minister – Abdoulkader Kamil Mohamed
Dominica
President – Charles Savarin Prime Minister – Roosevelt Skerrit
Dominican Republic
President – Danilo Medina
East Timor
President – Francisco Guterres Prime Minister – Mari Alkatiri
Ecuador
President – Lenín Moreno
Egypt
President – Abdel Fattah el-Sisi Prime Minister – Sherif Ismail
El Salvador
President – Salvador Sánchez Cerén
Equatorial Guinea
President – Teodoro Obiang Nguema Mbasogo[α] Prime Minister – Francisco Pascual Obama Asue
Eritrea
President – Isaias Afwerki
Estonia
President – Kersti Kaljulaid Prime Minister – Jüri Ratas
Ethiopia
President – Mulatu Teshome Prime Minister – Abiy Ahmed
Fiji
President – George Konrote Prime Minister – Frank Bainimarama
Finland
President – Sauli Niinistö Prime Minister – Juha Sipilä
France
President – Emmanuel Macron[β] Prime Minister – Édouard Philippe
Gabon
President – Ali Bongo Ondimba[α] Prime Minister – Emmanuel Issoze-Ngondet
Gambia, The
President – Adama Barrow
Georgia
President – Giorgi Margvelashvili Prime Minister – Giorgi Kvirikashvili
Germany
President – Frank-Walter Steinmeier Chancellor – Angela Merkel
Ghana
President – Nana Akufo-Addo
Greece
President – Prokopis Pavlopoulos Prime Minister – Alexis Tsipras
Grenada
Queen – Elizabeth II[γ]
Governor-General – Dame Cécile La Grenade Prime Minister – Keith Mitchell
Guatemala
President – Jimmy Morales
Guinea
President – Alpha Condé[α] Prime Minister – Mamady Youla
Guinea-Bissau
President – José Mário Vaz Prime Minister – Aristides Gomes
Guyana
President – David A. Granger[α] Prime Minister – Moses Nagamootoo
Haiti
President – Jovenel Moïse Prime Minister – Jack Guy Lafontant
Honduras
President – Juan Orlando Hernández
Hungary
President – János Áder Prime Minister – Viktor Orbán
Iceland
President – Guðni Th. Jóhannesson Prime Minister – Katrín Jakobsdóttir
India
President – Ram Nath Kovind Prime Minister – Narendra Modi
Indonesia
President – Joko Widodo
Iran
Supreme Leader – Ali Khamenei President – Hassan Rouhani
Iraq
President – Fuad Masum Prime Minister – Haider al-Abadi
Ireland
President – Michael D. Higgins Taoiseach – Leo Varadkar
Israel
President – Reuven Rivlin Prime Minister – Benjamin Netanyahu
Italy
President – Sergio Mattarella President of the Council of Ministers – Paolo Gentiloni
Ivory Coast
President – Alassane Ouattara[α] Prime Minister – Amadou Gon Coulibaly
Jamaica
Queen – Elizabeth II[γ]
Governor-General – Sir Patrick Allen Prime Minister – Andrew Holness
Japan
Emperor – Akihito Prime Minister – Shinzō Abe
Jordan
King – Abdullah II Prime Minister – Hani Al-Mulki
Kazakhstan
President – Nursultan Nazarbayev Prime Minister – Bakhytzhan Sagintayev
Kenya
President – Uhuru Kenyatta
Kiribati
President – Taneti Mamau
Kuwait
Emir – Sheikh Sabah Al-Ahmad Al-Jaber Al-Sabah Prime Minister – Sheikh Jaber Al-Mubarak Al-Hamad Al-Sabah
Kyrgyzstan
President – Sooronbay Jeenbekov Prime Minister – Sapar Isakov
Prime minister-designate – Muhammedkalyi Abilgaziyev
Laos
General Secretary of the Communist Party – Bounnhang Vorachith
President – Bounnhang Vorachith Prime Minister – Thongloun Sisoulith
Latvia
President – Raimonds Vējonis Prime Minister – Māris Kučinskis
Lebanon
President – Michel Aoun President of the Council of Ministers – Saad Hariri
Lesotho
King – Letsie III Prime Minister – Tom Thabane
Liberia
President – George Weah
Libya
Chairman of the Presidential Council and Prime Minister – Fayez al-Sarraj
Liechtenstein
Prince Regnant – Hans-Adam II Head of Government – Adrian Hasler
Regent – Hereditary Prince Alois
Lithuania
President – Dalia Grybauskaitė Prime Minister – Saulius Skvernelis
Luxembourg
Grand Duke – Henri Prime Minister – Xavier Bettel
Macedonia
President – Gjorge Ivanov President of the Government – Zoran Zaev
Madagascar
President – Hery Rajaonarimampianina Prime Minister – Olivier Mahafaly Solonandrasana
Malawi
President – Peter Mutharika
Malaysia
Yang di-Pertuan Agong – Muhammad V Prime Minister – Najib Razak
Maldives
President – Abdulla Yameen
Mali
President – Ibrahim Boubacar Keïta Prime Minister – Soumeylou Boubèye Maïga
Malta
President – Marie Louise Coleiro Preca Prime Minister – Joseph Muscat
Marshall Islands
President – Hilda Heine
Mauritania
President – Mohamed Ould Abdel Aziz Prime Minister – Yahya Ould Hademine
Mauritius
Acting President – Barlen Vyapoory Prime Minister – Pravind Jugnauth
Mexico
President – Enrique Peña Nieto
Micronesia
President – Peter M. Christian
Moldova
President – Igor Dodon Prime Minister – Pavel Filip
Monaco
Sovereign Prince – Albert II Minister of State – Serge Telle
Mongolia
President – Khaltmaagiin Battulga Prime Minister – Ukhnaagiin Khürelsükh
Montenegro
President – Filip Vujanović
President-elect – Milo Đukanović Prime Minister – Duško Marković
Morocco
King – Mohammed VI Head of Government – Saadeddine Othmani
Mozambique
President – Filipe Nyusi[α] Prime Minister – Carlos Agostinho do Rosário
Myanmar
President – Win Myint[α] State Counsellor – Aung San Suu Kyi
Namibia
President – Hage Geingob[α] Prime Minister – Saara Kuugongelwa
Nauru
President – Baron Waqa
Nepal
President – Bidhya Devi Bhandari Prime Minister – Khadga Prasad Oli
Netherlands
King – Willem-Alexander Prime Minister – Mark Rutte
New Zealand
Queen – Elizabeth II[γ]
Governor-General – Dame Patsy Reddy[ζ] Prime Minister – Jacinda Ardern
Nicaragua
President – Daniel Ortega
Niger
President – Mahamadou Issoufou Prime Minister – Brigi Rafini
Nigeria
President – Muhammadu Buhari
Norway
King – Harald V Prime Minister – Erna Solberg
North Korea
Chairman of the Workers' Party of Korea – Kim Jong-un
Supreme Leader and Chairman of the State Affairs Commission – Kim Jong-un[η]
Chairman of the Presidium of the Supreme People's Assembly – Kim Yong-nam[θ] Premier of the Cabinet – Pak Pong-ju
Oman
Sultan and Prime Minister – Qaboos bin Said al Said
Pakistan
President – Mamnoon Hussain Interim Prime Minister – Shahid Khaqan Abbasi
Palau
President – Tommy Remengesau
Palestine
President – Mahmoud Abbas Prime Minister – Rami Hamdallah
Panama
President – Juan Carlos Varela
Papua New Guinea
Queen – Elizabeth II[γ]
Governor-General – Sir Bob Dadae Prime Minister – Peter O'Neill
Paraguay
President – Horacio Cartes
Peru
President – Martín Vizcarra[α] Prime Minister – César Villanueva
Philippines
President – Rodrigo Duterte
Poland
President – Andrzej Duda Prime Minister – Mateusz Morawiecki
Portugal
President – Marcelo Rebelo de Sousa Prime Minister – António Costa
Qatar
Emir – Sheikh Tamim bin Hamad Al Thani Prime Minister – Sheikh Abdullah bin Nasser bin Khalifa Al Thani
Romania
President – Klaus Iohannis Prime Minister – Viorica Dăncilă
Russia
President – Vladimir Putin Prime Minister – Dmitry Medvedev
Rwanda
President – Paul Kagame[α] Prime Minister – Edouard Ngirente
Saint Kitts and Nevis
Queen – Elizabeth II[γ]
Governor-General – Sir Tapley Seaton Prime Minister – Timothy Harris
Saint Lucia
Queen – Elizabeth II[γ]
Governor-General – Sir Neville Cenac Prime Minister – Allen Chastanet
Saint Vincent and the Grenadines
Queen – Elizabeth II[γ]
Governor-General – Sir Frederick Ballantyne Prime Minister – Ralph Gonsalves
Samoa
O le Ao o le Malo – Va'aletoa Sualauvi II Prime Minister – Tuilaepa Aiono Sailele Malielegaoi
San Marino
Captain Regent[ι] – Stefano Palmieri
Captain Regent[ι] – Matteo Ciacci
São Tomé and Príncipe
President – Evaristo Carvalho Prime Minister – Patrice Trovoada
Saudi Arabia
King and Prime Minister – Salman
Senegal
President – Macky Sall Prime Minister – Mohammed Dionne
Serbia
President – Aleksandar Vučić Prime Minister – Ana Brnabić
Seychelles
President – Danny Faure
Sierra Leone
President – Julius Maada Bio
Singapore
President – Halimah Yacob Prime Minister – Lee Hsien Loong
Slovakia
President – Andrej Kiska Prime Minister – Peter Pellegrini
Slovenia
President – Borut Pahor Prime Minister – Miro Cerar
Solomon Islands
Queen – Elizabeth II[γ]
Governor-General – Sir Frank Kabui Prime Minister – Rick Houenipwela
Somalia
President – Mohamed Abdullahi Mohamed Prime Minister – Hassan Ali Khayre
South Africa
President – Cyril Ramaphosa
South Korea
President – Moon Jae-in[α] Prime Minister – Lee Nak-yeon
South Sudan
President – Salva Kiir Mayardit
Spain
King – Felipe VI President of the Government – Mariano Rajoy
Sri Lanka
President – Maithripala Sirisena[α] Prime Minister – Ranil Wickremesinghe
Sudan
President – Omar al-Bashir[α] Prime Minister – Bakri Hassan Saleh
Suriname
President – Dési Bouterse
Swaziland
King – Mswati III Prime Minister – Barnabas Sibusiso Dlamini
Sweden
King – Carl XVI Gustaf Prime Minister – Stefan Löfven
Switzerland
Federal Council[κ]
Alain Berset (as President)
Ueli Maurer (as Vice President)
Doris Leuthard (as Member)
Simonetta Sommaruga (as Member)
Johann Schneider-Ammann (as Member)
Guy Parmelin (as Member)
Ignazio Cassis (as Member)
Syria
President – Bashar al-Assad Prime Minister – Imad Khamis
Tajikistan
President – Emomali Rahmon[α] Prime Minister – Kokhir Rasulzoda
Tanzania
President – John Magufuli[α] Prime Minister – Kassim Majaliwa
Thailand
King – Maha Vajiralongkorn Prime Minister – Prayut Chan-o-cha
Togo
President – Faure Gnassingbé[α] Prime Minister – Komi Sélom Klassou
Tonga
King – Tupou VI Prime Minister – ʻAkilisi Pōhiva
Trinidad and Tobago
President – Paula-Mae Weekes Prime Minister – Keith Rowley
Tunisia
President – Beji Caid Essebsi Head of Government – Youssef Chahed
Turkey
President – Recep Tayyip Erdoğan[λ] Prime Minister – Binali Yıldırım
Turkmenistan
President – Gurbanguly Berdimuhamedow
Tuvalu
Queen – Elizabeth II[γ]
Governor-General – Sir Iakoba Italeli Prime Minister – Enele Sopoaga
Uganda
President – Yoweri Museveni[α] Prime Minister – Ruhakana Rugunda
Ukraine
President – Petro Poroshenko Prime Minister – Volodymyr Groysman
United Arab Emirates
President – Sheikh Khalifa bin Zayed Al Nahyan Prime Minister – Sheikh Mohammed bin Rashid Al Maktoum
United Kingdom
Queen – Elizabeth II[γ] Prime Minister – Theresa May
United States
President – Donald Trump
Uruguay
President – Tabaré Vázquez
Uzbekistan
President – Shavkat Mirziyoyev[α] Prime Minister – Abdulla Aripov
Vanuatu
President – Tallis Obed Moses Prime Minister – Charlot Salwai
Vatican City
Sovereign – Pope Francis President of the Governorate – Cardinal Giuseppe Bertello
Venezuela
President – Nicolás Maduro
Vietnam
General Secretary of the Communist Party – Nguyễn Phú Trọng
President – Trần Đại Quang Prime Minister – Nguyễn Xuân Phúc
Yemen
President – Abdrabbuh Mansur Hadi Prime Minister – Ahmed Obeid bin Daghr
Zambia
President – Edgar Lungu
Zimbabwe
President – Emmerson Mnangagwa
Other states
The following states control their territory and are recognised by at least one UN member state.
State
Also claimed by
Head of state
Head of government
Abkhazia
Georgia
President – Raul Khajimba Prime Minister – Beslan Bartsits
Cook Islands[μ]
New Zealand
Queen – Elizabeth II[γ]
Queen's Representative – Tom Marsters Prime Minister – Henry Puna
Kosovo
Serbia
President – Hashim Thaçi Prime Minister – Ramush Haradinaj
Niue[μ]
New Zealand
Queen – Elizabeth II[γ]
Governor-General – Dame Patsy Reddy[ζ] Premier – Sir Toke Talagi
Northern Cyprus
Cyprus
President – Mustafa Akıncı Prime Minister – Tufan Erhürman
Sahrawi Arab Democratic Republic
Morocco
General Secretary of the Polisario Front – Brahim Ghali
President – Brahim Ghali Prime Minister – Mohamed Wali Akeik
South Ossetia
Georgia
President – Anatoliy Bibilov Prime Minister – Erik Pukhayev
Taiwan (Republic of China)
People's Republic of China
President – Tsai Ing-wen President of the Executive Yuan – William Lai
The following states/governments control their territory, but are not recognised by any UN member states.
State/Government
Also claimed by
Head of state
Head of government
Artsakh
Azerbaijan
President – Bako Sahakyan
Somaliland
Somalia
President – Muse Bihi Abdi
Transnistria
Moldova
President – Vadim Krasnoselsky Prime Minister – Aleksandr Martynov
Other governments
These alternative governments are recognised as a sovereign state by at least one UN member.
Government
Also claimed by
Head of state
Head of government
House of Representatives
Libya
President of the House of Representatives – Aguila Saleh Issa Prime Minister – Abdullah al-Thani
Supreme Political Council
Yemen
President of the Supreme Political Council – Saleh Ali al-Sammad Prime Minister – Abdel-Aziz bin Habtour
Syrian Interim Government
Syria
President – Riad Seif Prime Minister – Jawad Abu Hatab
Other entities
Entity
Head of state
Head of government
European Union
President of the European Council – Donald Tusk President of the European Commission – Jean-Claude Juncker
Sovereign Military Order of Malta
Acting Lieutenant and Grand Master – Giacomo dalla Torre del Tempio di Sanguinetto Grand Chancellor – Albrecht Freiherr von Boeselager
See also
International relations portal
Politics portal
List of countries by system of government
List of current longest ruling non-royal national leaders
List of current state leaders by date of assumption of office
List of current presidents
List of current sovereign monarchs
List of current vice presidents and designated acting presidents
List of current prime ministers
List of current foreign ministers
List of current presidents of assembly
List of current dependent territory leaders
List of elected and appointed female heads of state and government
List of leaders of dependent territories
List of longest-ruling non-royal national leaders since 1900
List of the oldest living state leaders
List of national governments
Lists of state leaders
Lists of state leaders by year
List of state leaders in 2018
Notes
^ Jump up to: a b c d e f g h i j k l m n o p q r s t u v w In this state, the president is both head of state and of government; the office of prime minister may exist in these states, but it does not direct executive power (neither does the Afghan Chief Executive nor the Myanma/Burmese State Counsellor, either).
^ Jump up to: a b The President of France and the French Co-Prince of Andorra are positions held by the same person.
^ Jump up to: a b c d e f g h i j k l m n o p q r Constitutionally, Elizabeth II is separately and equally monarch of 16 sovereign states (alongside the United Kingdom) known collectively as the Commonwealth realms. In each of these states, with the exception of the UK (where she permanently resides) she is duly represented at the national level by a governor-general.
Jump up ^ The three-member Bosnian presidency is the head of state collectively.
Jump up ^ Temer assumed the Brazilian presidential powers and duties during the course of the suspension of Dilma Rousseff on 12 May 2016. Temer assumed the presidency outright when Rousseff was convicted and removed from office via impeachment on 31 August 2016.
^ Jump up to: a b The Governor-General of New Zealand and the Governor-General of Niue are positions held by the same person.
Jump up ^ The term "Supreme Leader" is used as a description (for the sake of brevity) rather than being an official title of a single office. The three actual offices held by Kim are:
Chairman of the Workers' Party of Korea
Chairman of the State Affairs Commission
Supreme Commander of the Korean People's Army
Jump up ^ The President (otherwise known as Chairman) of the Presidium of the Supreme People's Assembly accepts the credentials of foreign ambassadors, signs treaties, receives visiting heads of state, and represents North Korea on all state visits (ceremonial functions usually performed by heads of state in other states). The president has held these duties since 1998, when the constitution was revised.
^ Jump up to: a b Since 2016, the Grand and General Council of San Marino has held a larger proportion of seats for the United Left than those for the Popular Alliance; it can thus be inferred that the partner belonging to the former party exercises wider legislative capabilities than the latter through its parliamentary superiority, outnumbering the latter party by 3 seats.
Jump up ^ The seven-member Swiss Federal Council is collectively head of state and government. As a party to the Council, the President serves solely in a primus inter pares capacity for one year.
Jump up ^ Until the ratification of the Turkish constitutional referendum, Erdoğan remains ostensibly barred from wielding political power.
^ Jump up to: a b States in free association with New Zealand.
External links
CIDOB Foundation (in Spanish)—contextualised biographies of world political leaders
EmilePhaneuf—an archived, partial list of official websites for heads of state
Portale Storia (in Spanish)—a list of current rulers by country
Rulers—a list of rulers throughout time and places
United Nations—a list of heads of state, heads of government, and foreign ministers
WorldStatesmen—an online encyclopedia of the leaders of nations and territories
[show]
Links to related articles
[show]
v
t
e
Lists of state leaders by century
4th–3rd mill. BC
4th–3rd millennia BC
2nd millennium BC
20th century
19th
18th
17th
16th
15th
14th
13th
12th
11th
1st millennium BC
10th
9th
8th
7th
6th
5th
4th
3rd
2nd
1st BC
1st millennium
1st
2nd
3rd
4th
5th
6th
7th
8th
9th
10th
2nd millennium
11th
12th
13th
14th
15th
16th
17th
18th
19th
20th
1901–1950
1951–2000
3rd millennium
21st
Current
[show]
v
t
e
Heads of state and government of Africa
Heads of state
UN member states
Algeria
Angola
Benin
Botswana
Burkina Faso
Burundi
Cameroon
Cape Verde
Central African Republic
Chad
Comoros
Democratic Republic of the Congo
Republic of the Congo
Djibouti
Egypt
Equatorial Guinea
Eritrea
Ethiopia
Gabon
The Gambia
Ghana
Guinea
Guinea-Bissau
Ivory Coast
Kenya
Lesotho
Liberia
Libya
Madagascar
Malawi
Mali
Mauritania
Mauritius
Morocco
Mozambique
Namibia
Niger
Nigeria
Rwanda
São Tomé and Príncipe
Senegal
Seychelles
Sierra Leone
Somalia
South Africa
South Sudan
Sudan
Swaziland
Tanzania
Togo
Tunisia
Uganda
Zambia
Zimbabwe
Other states
Sahrawi Arab Democratic Republic
Somaliland
Heads of government
UN member states
Algeria
Angola
Benin
Botswana
Burkina Faso
Burundi
Cameroon
Cape Verde
Central African Republic
Chad
Comoros
Democratic Republic of the Congo
Republic of the Congo
Djibouti
Egypt
Equatorial Guinea
Eritrea
Ethiopia
Gabon
The Gambia
Ghana
Guinea
Guinea-Bissau
Ivory Coast
Kenya
Lesotho
Liberia
Libya
Madagascar
Malawi
Mali
Mauritania
Mauritius
Morocco
Mozambique
Namibia
Niger
Nigeria
Rwanda
São Tomé and Príncipe
Senegal
Seychelles
Sierra Leone
Somalia
South Africa
South Sudan
Sudan
Swaziland
Tanzania
Togo
Tunisia
Uganda
Zambia
Zimbabwe
Other states
Sahrawi Arab Democratic Republic
Somaliland
Defunct states
and governments
Belgian Congo
Governor-General
Burundi
King
Prime Minister
Ethiopia
Emperor (list)
Malawi
Prime Minister
Kenya
Prime Minister
Rwanda
King
Rhodesia
President
Prime Minister
Southern Rhodesia
Governor
South Africa
Governor-General
State President
Prime Minister
Sudan
Governor-General
Zanzibar
Sultan
Prime Minister
Zambia
Prime Minister
Zimbabwe
Prime Minister
[show]
v
t
e
Heads of state and government of the Americas
Heads
of state
UN members
and observers
Antigua and Barbuda
Argentina
Bahamas
Barbados
Belize
Bolivia
Brazil
Canada
Chile
Colombia
Costa Rica
Cuba
Dominica
Dominican Republic
Ecuador
El Salvador
Grenada
Guatemala
Guyana
Haiti
Honduras
Jamaica
Mexico
Nicaragua
Panama
Paraguay
Peru
Saint Kitts and Nevis
Saint Lucia
Saint Vincent and the Grenadines
Suriname
Trinidad and Tobago
United States
Uruguay
Venezuela
Dependencies and
other territories
Anguilla
Aruba
Bermuda
Bonaire
Cayman Islands
Falkland Islands
French Guiana
Greenland
Guadeloupe
Martinique
Montserrat
Navassa Island
Puerto Rico
Saba
Saint Barthélemy
Saint Martin
Sint Eustatius
Sint Maarten
South Georgia and the South Sandwich Islands
Turks and Caicos Islands
United States Virgin Islands
Heads of
government
UN members
and observers
Antigua and Barbuda
Argentina
Bahamas
Barbados
Belize
Bolivia
Brazil
Canada
Chile
Colombia
Costa Rica
Cuba
Dominica
Dominican Republic
Ecuador
El Salvador
Grenada
Guatemala
Guyana
Haiti
Honduras
Jamaica
Mexico
Nicaragua
Panama
Paraguay
Peru
Saint Kitts and Nevis
Saint Lucia
Saint Vincent and the Grenadines
Suriname
Trinidad and Tobago
United States
Uruguay
Venezuela
Dependencies and
other territories
Anguilla
Aruba
Bermuda
Bonaire
Cayman Islands
Falkland Islands
French Guiana
Greenland
Guadeloupe
Martinique
Montserrat
Navassa Island
Puerto Rico
Saba
Saint Barthélemy
Saint Martin
Sint Eustatius
Sint Maarten
South Georgia and the South Sandwich Islands
Turks and Caicos Islands
United States Virgin Islands
[show]
v
t
e
Heads of state and government of Asia
Heads
of state
UN members
and observers
Afghanistan
Armenia1
Azerbaijan1
Bahrain
Bangladesh
Bhutan
Brunei
Cambodia
China
Cyprus
East Timor
Georgia1
India
Indonesia
Iran
Iraq
Israel
Japan
Jordan
Kazakhstan
Kuwait
Kyrgyzstan
Laos
Lebanon
Malaysia
Maldives
Mongolia
Myanmar
Nepal
North Korea
Oman
Pakistan
Palestine
Philippines
Qatar
Russia1
Saudi Arabia
Singapore
Sri Lanka
South Korea
Syria
Tajikistan
Thailand
Turkey
Turkmenistan
United Arab Emirates
Uzbekistan
Vietnam
Yemen
special administrative regions
and limited recognised states
Abkhazia1
Hong Kong
Macau
Nagorno-Karabakh1
Northern Cyprus1
South Ossetia1
Taiwan
Heads of
government
UN members
and observers
Afghanistan
Armenia1
Azerbaijan1
Bahrain
Bangladesh
Bhutan
Brunei
Cambodia
China
Cyprus
East Timor
Georgia1
India
Indonesia
Iran
Iraq
Israel
Japan
Jordan
Kazakhstan
Kuwait
Kyrgyzstan
Laos
Lebanon
Malaysia
Maldives
Mongolia
Myanmar
Nepal
North Korea
Oman
Pakistan
Palestine
Philippines
Qatar
Russia1
Saudi Arabia
Singapore
Sri Lanka
South Korea
Syria
Tajikistan
Thailand
Turkey
Turkmenistan
United Arab Emirates
Uzbekistan
Vietnam
Yemen
special administrative regions
and limited recognised states
Abkhazia1
Hong Kong
Macau
Nagorno-Karabakh1
Northern Cyprus1
South Ossetia1
Taiwan
1 Partially or entirely in Asia, depending on the definition of the Europe–Asia border.
[show]
v
t
e
Heads of state and government of Europe
Heads
of state
UN members
and observers
Albania
Andorra
Armenia1
Austria
Azerbaijan1
Belarus
Belgium
Bosnia and Herzegovina
Bulgaria
Croatia
Cyprus1
Czech Republic
Denmark
Estonia
Finland
France
Georgia1
Germany
Greece
Hungary
Iceland
Ireland
Italy
Kazakhstan1
Latvia
Liechtenstein
Lithuania
Luxembourg
Macedonia
Malta
Moldova
Monaco
Montenegro
Netherlands
Norway
Poland
Portugal
Romania
Russian Federation1
San Marino
Serbia
Slovakia
Slovenia
Sovereign Military Order of Malta
Spain
Sweden
Switzerland
Turkey1
Ukraine
United Kingdom
Vatican City
Partially recognised2
Abkhazia1
Kosovo
Northern Cyprus1
South Ossetia1
Unrecognised states3
Artsakh1
Transnistria
Former countries
Czechoslovakia
East Germany
Serbia and Montenegro
Soviet Union1
Yugoslavia
Heads of
government
UN members
and observers
Albania
Andorra
Armenia1
Austria
Azerbaijan1
Belarus
Belgium
Bosnia and Herzegovina
Bulgaria
Croatia
Cyprus1
Czech Republic
Denmark
Estonia
Finland
France
Georgia1
Germany
Greece
Hungary
Iceland
Ireland
Italy
Kazakhstan1
Latvia
Liechtenstein
Lithuania
Luxembourg
Macedonia
Malta
Moldova
Monaco
Montenegro
Netherlands
Norway
Poland
Portugal
Romania
Russian Federation1
San Marino
Serbia
Slovakia
Slovenia
Sovereign Military Order of Malta
Spain
Sweden
Switzerland
Turkey1
Ukraine
United Kingdom
Vatican City
Partially recognised2
Abkhazia1
Kosovo
Northern Cyprus1
South Ossetia1
Unrecognised states3
Artsakh1
Transnistria
Former countries
Czechoslovakia
East Germany
Serbia and Montenegro
Soviet Union1
Yugoslavia
1. Partially or entirely in Asia, depending on geographical definition.
2. Recognised by at least one United Nations member.
3. Not recognised by any United Nations members.
[show]
v
t
e
Heads of state and government of Oceania
Heads of state
Sovereign states
Australia
Fiji
Kiribati
Marshall Islands
Federated States of Micronesia
Nauru
New Zealand
Palau
Papua New Guinea
Samoa
Solomon Islands
Tonga
Tuvalu
Vanuatu
Associated states of New Zealand
Cook Islands
Niue
Heads of government
Sovereign states
Australia
Fiji
Kiribati
Marshall Islands
Federated States of Micronesia
Nauru
New Zealand
Palau
Papua New Guinea
Samoa
Solomon Islands
Tonga
Tuvalu
Vanuatu
Associated states of New Zealand
Cook Islands
Niue
Retrieved from "https://en.wikipedia.org/w/index.php?title=List_of_current_heads_of_state_and_government&oldid=837289259"
Categories:
Lists of current office-holders
Lists of heads of state
Lists of heads of government
Hidden categories:
Wikipedia pages semi-protected against vandalism
Pages using div col without cols and colwidth parameters
Pages using Columns-list with deprecated parameters
Articles with Spanish-language external links
Use dmy dates from January 2016
Use British English from January 2016
Navigation menu
Personal tools
Not logged in
Talk
Contributions
Create account
Log in
Namespaces
Article
Talk
Variants
Views
Read
View source
View history
More
Search
Navigation
Main page
Contents
Featured content
Current events
Random article
Donate to Wikipedia
Wikipedia store
Interaction
Help
About Wikipedia
Community portal
Recent changes
Contact page
Tools
What links here
Related changes
Upload file
Special pages
Permanent link
Page information
Wikidata item
Cite this page
Print/export
Create a book
Download as PDF
Printable version
In other projects
Wikidata
Languages
العربية
বাংলা
Cymraeg
Eesti
Ελληνικά
Español
Esperanto
Français
Gagauz
हिन्दी
Hrvatski
Bahasa Indonesia
Italiano
Қазақша
मराठी
მარგალური
日本語
Norsk
Oʻzbekcha/ўзбекча
ਪੰਜਾਬੀ
پښتو
Polski
Português
Reo tahiti
Русский
Scots
Simple English
Slovenščina
Српски / srpski
Suomi
Svenska
ไทย
Türkçe
Українська
Tiếng Việt
Yorùbá
中文
28 more
Edit links
This page was last edited on 19 April 2018, at 22:10.
Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.
Privacy policy
About Wikipedia
Disclaimers
Contact Wikipedia
Developers
Cookie statement
Mobile view
Enable previews

values: mw-page-base noprint

values: mw-head-base noprint

values: This article is semi-protected until June 29, 2018, due to vandalism

values: firstHeading firstHeading en

values: siteSub noprint

values: jump-to-nav mw-jump

values:
note
hatnote navigation-not-searchable

values: List of state leaders in the 21st century

value: b

values:
/wiki/Executive_branch
mw-redirect
Executive branch

values: border-left: 1.2em solid; border-left-color: LightYellow; padding-left: 0.4em;

values:
https://en.wiktionary.org/wiki/de_jure
extiw
wikt:de jure

values: list-style-type: none; list-style-image: none; text-indent: -1.5em; margin: 0;

values: border-left: 1.2em solid; border-left-color: LightCyan; padding-left: 0.4em;

values:
https://en.wiktionary.org/wiki/de_facto
extiw
wikt:de facto

values: List of countries by system of government

values:
/wiki/Prime_Minister_of_Andorra
mw-redirect
Prime Minister of Andorra

values:
/wiki/Prime_Minister_of_Belarus
mw-redirect
Prime Minister of Belarus

values:
/wiki/Prime_Minister_of_Belize
mw-redirect
Prime Minister of Belize

values:
/wiki/President_of_Benin
mw-redirect
President of Benin

values:
/wiki/Prime_Minister_of_Bhutan
mw-redirect
Prime Minister of Bhutan

values: High Representative for Bosnia and Herzegovina

values: Chairman of the Council of Ministers of Bosnia and Herzegovina

values: Chairmen of the Presidency of Bosnia and Herzegovina

values:
/wiki/Sultan_of_Brunei
mw-redirect
Sultan of Brunei

values:
/wiki/President_of_Burkina_Faso
mw-redirect
President of Burkina Faso

values:
/wiki/Prime_Minister_of_Burkina_Faso
mw-redirect
Prime Minister of Burkina Faso

values:
/wiki/President_of_Burundi
mw-redirect
President of Burundi

values:
/wiki/King_of_Cambodia
mw-redirect
King of Cambodia

values:
/wiki/President_of_Cape_Verde
mw-redirect
President of Cape Verde

values:
/wiki/Prime_Minister_of_Cape_Verde
mw-redirect
Prime Minister of Cape Verde

values: President of the Central African Republic

values: Prime Minister of the Central African Republic

values:
/wiki/President_of_Chad
mw-redirect
President of Chad

values:
/wiki/Prime_Minister_of_Chad
mw-redirect
Prime Minister of Chad

values: General Secretary of the Communist Party of China

values: President of the People's Republic of China

values: Premier of the People's Republic of China

values:
/wiki/President_of_the_Comoros
mw-redirect
President of the Comoros

values: President of the Democratic Republic of the Congo

values: Prime Minister of the Democratic Republic of the Congo

values: Prime Minister of the Republic of the Congo

values: First Secretary of the Communist Party of Cuba

values:
/wiki/President_of_Djibouti
mw-redirect
President of Djibouti

values:
/wiki/Prime_Minister_of_Djibouti
mw-redirect
Prime Minister of Djibouti

values:
/wiki/President_of_Dominica
mw-redirect
President of Dominica

values:
/wiki/President_of_Equatorial_Guinea
mw-redirect
President of Equatorial Guinea

values:
/wiki/President_of_Eritrea
mw-redirect
President of Eritrea

values:
/wiki/Abiy_Ahmed_Ali
mw-redirect
Abiy Ahmed Ali

values:
/wiki/George_Konrote
mw-redirect
George Konrote

values:
/wiki/President_of_Gabon
mw-redirect
President of Gabon

values:
/wiki/Prime_Minister_of_Gabon
mw-redirect
Prime Minister of Gabon

values:
/wiki/Prime_Minister_of_Grenada
mw-redirect
Prime Minister of Grenada

values:
/wiki/President_of_Guinea
mw-redirect
President of Guinea

values:
/wiki/Prime_Minister_of_Guinea
mw-redirect
Prime Minister of Guinea

values:
/wiki/President_of_Guinea-Bissau
mw-redirect
President of Guinea-Bissau

values:
/wiki/Prime_Minister_of_Guinea-Bissau
mw-redirect
Prime Minister of Guinea-Bissau

values:
/wiki/Prime_Minister_of_Guyana
mw-redirect
Prime Minister of Guyana

values:
/wiki/President_of_the_Ivory_Coast
mw-redirect
President of the Ivory Coast

values:
/wiki/Prime_Minister_of_the_Ivory_Coast
mw-redirect
Prime Minister of the Ivory Coast

values:
/wiki/King_of_Jordan
mw-redirect
King of Jordan

values:
/wiki/Emir_of_Kuwait
mw-redirect
Emir of Kuwait

values:
/wiki/Prime_Minister_of_Kuwait
mw-redirect
Prime Minister of Kuwait

values: General Secretary of the Lao People's Revolutionary Party

values:
/wiki/King_of_Lesotho
mw-redirect
King of Lesotho

values:
/wiki/Prime_Minister_of_Lesotho
mw-redirect
Prime Minister of Lesotho

values: Chairman of the Presidential Council of Libya

values:
/wiki/Prime_Minister_of_Libya
mw-redirect
Prime Minister of Libya

values:
/wiki/Prime_Minister_of_Liechtenstein
mw-redirect
Prime Minister of Liechtenstein

values:
/wiki/Regent_of_Liechtenstein
mw-redirect
Regent of Liechtenstein

values: Alois, Hereditary Prince of Liechtenstein

values:
/wiki/President_of_Lithuania
mw-redirect
President of Lithuania

values:
/wiki/Grand_Duke_of_Luxembourg
mw-redirect
Grand Duke of Luxembourg

values:
/wiki/Prime_Minister_of_Luxembourg
mw-redirect
Prime Minister of Luxembourg

values:
/wiki/President_of_Madagascar
mw-redirect
President of Madagascar

values:
/wiki/President_of_Mali
mw-redirect
President of Mali

values:
/wiki/Prime_Minister_of_Mali
mw-redirect
Prime Minister of Mali

values:
/wiki/Marie_Louise_Coleiro_Preca
mw-redirect
Marie Louise Coleiro Preca

values:
/wiki/President_of_Mauritania
mw-redirect
President of Mauritania

values:
/wiki/Prime_Minister_of_Mauritania
mw-redirect
Prime Minister of Mauritania

values: President of the Federated States of Micronesia

values:
/wiki/King_of_Morocco
mw-redirect
King of Morocco

values:
/wiki/Prime_Minister_of_Morocco
mw-redirect
Prime Minister of Morocco

values:
/wiki/President_of_Mozambique
mw-redirect
President of Mozambique

values:
/wiki/Prime_Minister_of_Mozambique
mw-redirect
Prime Minister of Mozambique

values:
/wiki/Prime_Minister_of_Nepal
mw-redirect
Prime Minister of Nepal

values:
/wiki/President_of_Niger
mw-redirect
President of Niger

values:
/wiki/Prime_Minister_of_Niger
mw-redirect
Prime Minister of Niger

values: Chairman of the State Affairs Commission

values: Chairman of the Presidium of the Supreme People's Assembly

values:
/wiki/Sultan_of_Oman
mw-redirect
Sultan of Oman

values:
/wiki/Prime_Minister_of_Oman
mw-redirect
Prime Minister of Oman

values: Prime Minister of the State of Palestine

values:
/wiki/President_of_Panama
mw-redirect
President of Panama

values:
/wiki/Emir_of_Qatar
mw-redirect
Emir of Qatar

values:
/wiki/Prime_Minister_of_Qatar
mw-redirect
Prime Minister of Qatar

values: Abdullah bin Nasser bin Khalifa Al Thani

values:
/wiki/President_of_Rwanda
mw-redirect
President of Rwanda

values:
/wiki/Edouard_Ngirente
mw-redirect
Edouard Ngirente

values: Governor-General of Saint Kitts and Nevis

values:
/wiki/Prime_Minister_of_Saint_Lucia
mw-redirect
Prime Minister of Saint Lucia

values: Monarchy of Saint Vincent and the Grenadines

values: Governor-General of Saint Vincent and the Grenadines

values: Prime Minister of Saint Vincent and the Grenadines

values:
/wiki/Mohammed_Dionne
mw-redirect
Mohammed Dionne

values:
/wiki/President_of_Seychelles
mw-redirect
President of Seychelles

values:
/wiki/Prime_Minister_of_Somalia
mw-redirect
Prime Minister of Somalia

values:
/wiki/President_of_South_Sudan
mw-redirect
President of South Sudan

values:
/wiki/President_of_Sudan
mw-redirect
President of Sudan

values:
/wiki/Prime_Minister_of_Sudan
mw-redirect
Prime Minister of Sudan

values:
/wiki/King_of_Swaziland
mw-redirect
King of Swaziland

values:
/wiki/Prime_Minister_of_Swaziland
mw-redirect
Prime Minister of Swaziland

values:
/wiki/Swiss_Federal_Council
mw-redirect
Swiss Federal Council

values:
/wiki/President_of_Togo
mw-redirect
President of Togo

values:
/wiki/Prime_Minister_of_Togo
mw-redirect
Prime Minister of Togo

values:
/wiki/Monarchy_of_Tonga
mw-redirect
Monarchy of Tonga

values:
/wiki/Prime_Minister_of_Tunisia
mw-redirect
Prime Minister of Tunisia

values: Prime Minister of the United Arab Emirates

values: List of sovereigns of Vatican City State

values: President of the Pontifical Commission for Vatican City State

values: General Secretary of the Communist Party of Vietnam

values:
/wiki/Monarchy_of_Niue
mw-redirect
Monarchy of Niue

values: President of the Sahrawi Arab Democratic Republic

values: Prime Minister of the Sahrawi Arab Democratic Republic

values:
/wiki/Anatoliy_Bibilov
mw-redirect
Anatoliy Bibilov

values:
/wiki/President_of_Somaliland
mw-redirect
President of Somaliland

values: Aleksandr Martynov (Transnistrian politician)

values: President of the House of Representatives of Libya

values: President of the Supreme Political Council

values: President of the Syrian National Coalition

values: Prime Minister of the Syrian National Coalition

values: List of Princes and Grand Masters of the Sovereign Military Order of Malta

values: Giacomo dalla Torre del Tempio di Sanguinetto

values:
/wiki/Albrecht_Freiherr_von_Boeselager
mw-redirect
Albrecht Freiherr von Boeselager

values: display:table-cell;padding:0.2em 0.2em 0.2em 0.3em;vertical-align:middle

values: margin:0.5em 0 0.5em 1em;border:solid #aaa 1px

values: List of current longest ruling non-royal national leaders

values: List of current state leaders by date of assumption of office

values: List of current vice presidents and designated acting presidents

values:
/wiki/List_of_current_prime_ministers
mw-redirect
List of current prime ministers

values: List of current dependent territory leaders

values: List of leaders of dependent territories

values: List of longest-ruling non-royal national leaders since 1900

values: div-col columns column-count column-count-2

values: -moz-column-count: 2; -webkit-column-count: 2; column-count: 2;

values:
/wiki/Supreme_Leader
mw-redirect
Supreme Leader

values: Supreme Commander of the Korean People's Army

values:
nofollow
external text
http://emilephaneuf.com/?p=164

values:
nofollow
http://rulers.org/
external text

values:
nofollow
http://worldstatesmen.org/
external text

values: Template talk:State leaders by century (page does not exist)

values: List of state leaders in the 4th and 3rd millennia BC

values: List of state leaders in the 20th century BC

values: List of state leaders in the 19th century BC

values: List of state leaders in the 18th century BC

values: List of state leaders in the 17th century BC

values: List of state leaders in the 16th century BC

values: List of state leaders in the 15th century BC

values: List of state leaders in the 14th century BC

values: List of state leaders in the 13th century BC

values: List of state leaders in the 12th century BC

values: List of state leaders in the 11th century BC

values: List of state leaders in the 10th century BC

values: List of state leaders in the 9th century BC

values: List of state leaders in the 8th century BC

values: List of state leaders in the 7th century BC

values: List of state leaders in the 6th century BC

values: List of state leaders in the 5th century BC

values: List of state leaders in the 4th century BC

values: List of state leaders in the 3rd century BC

values: List of state leaders in the 2nd century BC

values: List of state leaders in the 1st century BC

values: List of state leaders in the 1st century

values: List of state leaders in the 2nd century

values: List of state leaders in the 3rd century

values: List of state leaders in the 4th century

values: List of state leaders in the 5th century

values: List of state leaders in the 6th century

values: List of state leaders in the 7th century

values: List of state leaders in the 8th century

values: List of state leaders in the 9th century

values: List of state leaders in the 10th century

values: List of state leaders in the 11th century

values: List of state leaders in the 12th century

values: List of state leaders in the 13th century

values: List of state leaders in the 14th century

values: List of state leaders in the 15th century

values: List of state leaders in the 16th century

values: List of state leaders in the 17th century

values: List of state leaders in the 18th century

values: List of state leaders in the 19th century

values: List of state leaders in the 20th century (1901–1950)

values: List of state leaders in the 20th century (1951–2000)

values: nowraplinks hlist collapsible autocollapse navbox-inner

values: Template:Heads of state and government of Africa

values: Template talk:Heads of state and government of Africa

values:
/wiki/Heads_of_state
mw-redirect
Heads of state

values: List of heads of state of the Central African Republic

values: List of Presidents of the Republic of the Congo

values: List of Presidents of São Tomé and Príncipe

values:
/wiki/List_of_Presidents_of_Zambia
mw-redirect
List of Presidents of Zambia

values:
/wiki/Heads_of_government
mw-redirect
Heads of government

values: List of heads of government of the Central African Republic

values: List of Prime Ministers of the Republic of the Congo

values: List of Prime Ministers of Equatorial Guinea

values: List of Prime Ministers of Guinea-Bissau

values: List of heads of government of Ivory Coast

values: List of heads of government of Mozambique

values: List of Prime Ministers of São Tomé and Príncipe

values: List of colonial governors of the Congo Free State and Belgian Congo

values:
/wiki/List_of_Kings_of_Burundi
mw-redirect
List of Kings of Burundi

values: Governor-General of the Union of South Africa

values: List of governors of pre-independence Sudan

values: nowraplinks collapsible autocollapse navbox-inner

values: Template:Heads of state and government of the Americas

values: Template talk:Heads of state and government of the Americas

values: width:1%;line-height: 1.3em; text-align: center;

values:
row
navbox-group
width:1%;line-height: 1.3em;

values: Monarchy of Anguilla (page does not exist)

values: Monarchy of Bermuda (page does not exist)

values: Monarchy of Bonaire (page does not exist)

values: Monarchy of Cayman Islands (page does not exist)

values: Monarchy of Falkland Islands (page does not exist)

values:
/wiki/Monarchy_of_Greenland
mw-redirect
Monarchy of Greenland

values: President of Guadeloupe (page does not exist)

values: President of Martinique (page does not exist)

values: Monarchy of Montserrat (page does not exist)

values: President of Navassa Island (page does not exist)

values: Monarchy of Sint Eustatius (page does not exist)

values: Monarchy of Sint Maarten (page does not exist)

values: Monarchy of South Georgia and the South Sandwich Islands (page does not exist)

values: Monarchy of Turks and Caicos Islands (page does not exist)

values: List of Governors of the United States Virgin Islands

values:
/wiki/Presidents_of_Paraguay
mw-redirect
Presidents of Paraguay

values:
/wiki/Prime_Minister_of_Suriname
mw-redirect
Prime Minister of Suriname

values:
/wiki/President_of_United_States
mw-redirect
President of United States

values:
/wiki/Premier_of_Bermuda
mw-redirect
Premier of Bermuda

values: Premier of Cayman Islands (page does not exist)

values: Commissioner of South Georgia and the South Sandwich Islands

values: Premier of Turks and Caicos Islands (page does not exist)

values: Template:Heads of state and government of Asia

values: Template talk:Heads of state and government of Asia

values:
/wiki/King_of_Bhutan
mw-redirect
King of Bhutan

values:
/wiki/President_of_Maldives
mw-redirect
President of Maldives

values:
/wiki/President_of_Palestine
mw-redirect
President of Palestine

values:
/wiki/King_of_Thailand
mw-redirect
King of Thailand

values: President of the Nagorno-Karabakh Republic

values:
/wiki/List_of_Presidents_of_Cyprus
mw-redirect
List of Presidents of Cyprus

values:
/wiki/List_of_Presidents_of_Maldives
mw-redirect
List of Presidents of Maldives

values:
/wiki/Prime_Minister_of_North_Korea
mw-redirect
Prime Minister of North Korea

values:
/wiki/Prime_Minister_of_Palestine
mw-redirect
Prime Minister of Palestine

values: Prime Minister of the Nagorno-Karabakh Republic

values: Template:Heads of state and government of Europe

values: Template talk:Heads of state and government of Europe

values: Chairman of the Presidency of Bosnia and Herzegovina

values: List of heads of state of the Soviet Union

values: List of heads of government of Liechtenstein

values: List of Prime Ministers of Czechoslovakia

values: Template:Heads of state and government of Oceania

values: Template talk:Heads of state and government of Oceania

values: nowraplinks collapsible collapsed navbox-inner

values: Category:Lists of current office-holders

values: Category:Wikipedia pages semi-protected against vandalism

values: Category:Pages using div col without cols and colwidth parameters

values: Category:Pages using Columns-list with deprecated parameters

values: Category:Articles with Spanish-language external links

values: Category:Use dmy dates from January 2016

values: Category:Use British English from January 2016

values: Discussion about edits from this IP address [ctrl-alt-n]

values: A list of edits made from this IP address [ctrl-alt-y]

values: You are encouraged to create an account and log in; however, it is not mandatory

values: You're encouraged to log in; however, it's not mandatory. [ctrl-alt-o]

values: Discussion about the content page [ctrl-alt-t]

values: p-namespaces navigation vectorTabs p-namespaces-label

values:
p-variants
navigation
vectorMenu emptyPortlet
p-variants-label

values:
This page is protected.
You can view its source [ctrl-alt-e]

values: Past revisions of this page [ctrl-alt-h]

values: p-views navigation vectorTabs p-views-label

values:
p-cactions
navigation
vectorMenu emptyPortlet
p-cactions-label

values:
mw-wiki-logo
/wiki/Main_Page
Visit the main page

values:
/wiki/Main_Page
Visit the main page [ctrl-alt-z]
z

values: Featured content – the best of Wikipedia

values: Find background information on current events

values:
/wiki/Special:Random
Load a random article [ctrl-alt-x]
x

values: portal navigation p-navigation p-navigation-label

values: Guidance on how to use and edit Wikipedia

values: About the project, what you can do, where to find things

values: A list of recent changes in the wiki [ctrl-alt-r]

values: portal navigation p-interaction p-interaction-label

values: List of all English Wikipedia pages containing links to this page [ctrl-alt-j]

values: Recent changes in pages linked from this page [ctrl-alt-k]

values:
/wiki/Wikipedia:File_Upload_Wizard
Upload files [ctrl-alt-u]
u

values: A list of all special pages [ctrl-alt-q]

values: Permanent link to this revision of the page

values: Link to connected data repository item [ctrl-alt-g]

values: Printable version of this page [ctrl-alt-p]

values: portal navigation p-wikibase-otherprojects p-wikibase-otherprojects-label

values: قائمة رؤساء الدول والحكومات الحاليين – Arabic

values: বর্তমান রাষ্ট্রপ্রধান ও সরকারপ্রধানদের তালিকা – Bangla

values: Rhestr arweinwyr gwladwriaethau cyfoes – Welsh

values:
interlanguage-link interwiki-cy
display: none;

values: Riigipeade ja valitsusjuhtide koondtabel – Estonian

values:
interlanguage-link interwiki-et
display: none;

values: Κατάλογος ηγετών των ανεξάρτητων κρατών του κόσμου – Greek

values:
interlanguage-link interwiki-el
display: none;

values: Anexo:Jefes de Estado y de Gobierno actuales – Spanish

values: Listo de aktualaj ŝtatestro kaj estroj de registaro – Esperanto

values:
interlanguage-link interwiki-eo
display: none;

values: Liste des dirigeants actuels des États – French

values: Baamsız devletlärin devlet hem Pravitelstva başkannarı listasi – Gagauz

values:
interlanguage-link interwiki-gag
display: none;

values: राज्य और सरकार के वर्तमान प्रमुखों की सूची – Hindi

values:
interlanguage-link interwiki-hr
display: none;

values: Capi di Stato e di governo in carica – Italian

values:
interlanguage-link interwiki-it
display: none;

values: Қазіргі қызметтегі мемлекет және үкімет басшылары – Kazakh

values:
interlanguage-link interwiki-kk
display: none;

values: जगातील देशांच्या राष्ट्रप्रमुख व सरकारप्रमुखांची यादी – Marathi

values:
interlanguage-link interwiki-mr
display: none;

values: მოქიმინჯე სახენწჷფოეფიშ დო თარობეფიშ მადუდეეფიშ ერკებული – Mingrelian

values:
interlanguage-link interwiki-xmf
display: none;

values: 世界各国の指導者一覧 – Japanese

values:
interlanguage-link interwiki-ja
display: none;

values: Liste over nåværende statsledere – Norwegian

values:
interlanguage-link interwiki-no
display: none;

values: Amaldagi davlat va hukumat rahbarlari – Uzbek

values:
interlanguage-link interwiki-uz
display: none;

values: ਮੁਲਕ ਅਤੇ ਸਰਕਾਰ ਦੇ ਵਰਤਮਾਨ ਮੁਖੀਆਂ ਦੀ ਸੂਚੀ – Punjabi

values:
interlanguage-link interwiki-pa
display: none;

values: د نړۍ برحاله هېوادمشران – Pashto

values:
interlanguage-link interwiki-ps
display: none;

values:
interlanguage-link interwiki-pl
display: none;

values: Lista de chefes de estado e de governo atuais – Portuguese

values: Tāpura o te mau taata faatere i te mau fenua o te ao nei – Tahitian

values:
interlanguage-link interwiki-ty
display: none;

values: Список действующих глав государств и правительств – Russian

values: Leet o current heids o state an govrenment – Scots

values:
interlanguage-link interwiki-sco
display: none;

values: List of national rulers – Simple English

values: Списак шефова држава и влада – Serbian

values: Luettelo nykyisistä valtioiden ja hallitusten päämiehistä – Finnish

values:
interlanguage-link interwiki-sv
display: none;

values: รายนามประมุขแห่งรัฐและหัวหน้ารัฐบาลปัจจุบัน – Thai

values: Günümüzdeki devlet ve hükûmet başkanları listesi – Turkish

values: Список чинних голів держав та урядів – Ukrainian

values:
interlanguage-link interwiki-vi
display: none;

values: Àtòjọ àwọn olórí ìjọba àti orílẹ̀-èdè lọ́wọ́lọ́wọ́ – Yoruba

values: 各国领导人列表 – Chinese

values: All languages (initial selection from common choices by you and others)

values: /static/images/wikimedia-button-1.5x.png 1.5x, /static/images/wikimedia-button-2x.png 2x

values: /static/images/poweredby_mediawiki_132x47.png 1.5x, /static/images/poweredby_mediawiki_176x62.png 2x

values: mediawiki ltr sitedir-ltr mw-hide-empty-elt ns-0 ns-subject page-List_of_current_heads_of_state_and_government rootpage-List_of_current_heads_of_state_and_government skin-vector action-view


text:
Data model
From Wikipedia, the free encyclopedia
Jump to: navigation, search
A data model (or datamodel[1][2][3][4][5]) is an abstract model that organizes elements of data and standardizes how they relate to one another and to properties of the real world entities. For instance, a data model may specify that the data element representing a car be composed of a number of other elements which, in turn, represent the color and size of the car and define its owner.
The term data model is used in two distinct but closely related senses. Sometimes it refers to an abstract formalization of the objects and relationships found in a particular application domain, for example the customers, products, and orders found in a manufacturing organization. At other times it refers to a set of concepts used in defining such formalizations: for example concepts such as entities, attributes, relations, or tables. So the "data model" of a banking application may be defined using the entity-relationship "data model". This article uses the term in both senses.
Overview of data modeling context: Data model is based on Data, Data relationship, Data semantic and Data constraint. A data model provides the details of information to be stored, and is of primary use when the final product is the generation of computer software code for an application or the preparation of a functional specification to aid a computer software make-or-buy decision. The figure is an example of the interaction between process and data models.[6]
A data model explicitly determines the structure of data. Data models are specified in a data modeling notation, which is often graphical in form.[7]
A data model can sometimes be referred to as a data structure, especially in the context of programming languages. Data models are often complemented by function models, especially in the context of enterprise models.
Contents
[hide]
1 Overview
1.1 The role of data models
1.2 Three perspectives
2 History
3 Types of data models
3.1 Database model
3.2 Data structure diagram
3.3 Entity-relationship model
3.4 Geographic data model
3.5 Generic data model
3.6 Semantic data model
4 Data model topics
4.1 Data architecture
4.2 Data modeling
4.3 Data properties
4.4 Data organization
4.5 Data structure
4.6 Data model theory
4.7 Patterns
5 Related models
5.1 Data flow diagram
5.2 Information model
5.3 Object model
5.4 Object-Role Model
5.5 Unified Modeling Language models
6 See also
7 References
8 Further reading
Overview[edit]
Managing large quantities of structured and unstructured data is a primary function of information systems. Data models describe the structure, manipulation and integrity aspects of the data stored in data management systems such as relational databases. They typically do not describe unstructured data, such as word processing documents, email messages, pictures, digital audio, and video.
The role of data models[edit]
How data models deliver benefit[8]
The main aim of data models is to support the development of information systems by providing the definition and format of data. According to West and Fowler (1999) "if this is done consistently across systems then compatibility of data can be achieved. If the same data structures are used to store and access data then different applications can share data. The results of this are indicated above. However, systems and interfaces often cost more than they should, to build, operate, and maintain. They may also constrain the business rather than support it. A major cause is that the quality of the data models implemented in systems and interfaces is poor".[8]
"Business rules, specific to how things are done in a particular place, are often fixed in the structure of a data model. This means that small changes in the way business is conducted lead to large changes in computer systems and interfaces".[8]
"Entity types are often not identified, or incorrectly identified. This can lead to replication of data, data structure, and functionality, together with the attendant costs of that duplication in development and maintenance".[8]
"Data models for different systems are arbitrarily different. The result of this is that complex interfaces are required between systems that share data. These interfaces can account for between 25-70% of the cost of current systems".[8]
"Data cannot be shared electronically with customers and suppliers, because the structure and meaning of data has not been standardized. For example, engineering design data and drawings for process plant are still sometimes exchanged on paper".[8]
The reason for these problems is a lack of standards that will ensure that data models will both meet business needs and be consistent.[8]
A data model explicitly determines the structure of data. Typical applications of data models include database models, design of information systems, and enabling exchange of data. Usually data models are specified in a data modeling language.[3]
Three perspectives[edit]
The ANSI/SPARC three level architecture. This shows that a data model can be an external model (or view), a conceptual model, or a physical model. This is not the only way to look at data models, but it is a useful way, particularly when comparing models.[8]
A data model instance may be one of three kinds according to ANSI in 1975:[9]
Conceptual data model : describes the semantics of a domain, being the scope of the model. For example, it may be a model of the interest area of an organization or industry. This consists of entity classes, representing kinds of things of significance in the domain, and relationship assertions about associations between pairs of entity classes. A conceptual schema specifies the kinds of facts or propositions that can be expressed using the model. In that sense, it defines the allowed expressions in an artificial 'language' with a scope that is limited by the scope of the model.
Logical data model : describes the semantics, as represented by a particular data manipulation technology. This consists of descriptions of tables and columns, object oriented classes, and XML tags, among other things.
Physical data model : describes the physical means by which data are stored. This is concerned with partitions, CPUs, tablespaces, and the like.
The significance of this approach, according to ANSI, is that it allows the three perspectives to be relatively independent of each other. Storage technology can change without affecting either the logical or the conceptual model. The table/column structure can change without (necessarily) affecting the conceptual model. In each case, of course, the structures must remain consistent with the other model. The table/column structure may be different from a direct translation of the entity classes and attributes, but it must ultimately carry out the objectives of the conceptual entity class structure. Early phases of many software development projects emphasize the design of a conceptual data model. Such a design can be detailed into a logical data model. In later stages, this model may be translated into physical data model. However, it is also possible to implement a conceptual model directly.
History[edit]
One of the earliest pioneering works in modelling information systems was done by Young and Kent (1958),[10][11] who argued for "a precise and abstract way of specifying the informational and time characteristics of a data processing problem". They wanted to create "a notation that should enable the analyst to organize the problem around any piece of hardware". Their work was a first effort to create an abstract specification and invariant basis for designing different alternative implementations using different hardware components. A next step in IS modelling was taken by CODASYL, an IT industry consortium formed in 1959, who essentially aimed at the same thing as Young and Kent: the development of "a proper structure for machine independent problem definition language, at the system level of data processing". This led to the development of a specific IS information algebra.[11]
In the 1960s data modeling gained more significance with the initiation of the management information system (MIS) concept. According to Leondes (2002), "during that time, the information system provided the data and information for management purposes. The first generation database system, called Integrated Data Store (IDS), was designed by Charles Bachman at General Electric. Two famous database models, the network data model and the hierarchical data model, were proposed during this period of time".[12] Towards the end of the 1960s, Edgar F. Codd worked out his theories of data arrangement, and proposed the relational model for database management based on first-order predicate logic.[13]
In the 1970s entity relationship modeling emerged as a new type of conceptual data modeling, originally proposed in 1976 by Peter Chen. Entity relationship models were being used in the first stage of information system design during the requirements analysis to describe information needs or the type of information that is to be stored in a database. This technique can describe any ontology, i.e., an overview and classification of concepts and their relationships, for a certain area of interest.
In the 1970s G.M. Nijssen developed "Natural Language Information Analysis Method" (NIAM) method, and developed this in the 1980s in cooperation with Terry Halpin into Object-Role Modeling (ORM). However, it was Terry Halpin's 1989 PhD thesis that created the formal foundation on which Object-Role Modeling is based. Ken Evans 13:11, 30 April 2017 (UTC)
Bill Kent, in his 1978 book Data and Reality,[14] compared a data model to a map of a territory, emphasizing that in the real world, "highways are not painted red, rivers don't have county lines running down the middle, and you can't see contour lines on a mountain". In contrast to other researchers who tried to create models that were mathematically clean and elegant, Kent emphasized the essential messiness of the real world, and the task of the data modeller to create order out of chaos without excessively distorting the truth.
In the 1980s, according to Jan L. Harrington (2000), "the development of the object-oriented paradigm brought about a fundamental change in the way we look at data and the procedures that operate on data. Traditionally, data and procedures have been stored separately: the data and their relationship in a database, the procedures in an application program. Object orientation, however, combined an entity's procedure with its data."[15]
Types of data models[edit]
123
Database model[edit]
Main article: Database model
A database model is a specification describing how a database is structured and used.
Several such models have been suggested. Common models include:
Flat model
This may not strictly qualify as a data model. The flat (or table) model consists of a single, two-dimensional array of data elements, where all members of a given column are assumed to be similar values, and all members of a row are assumed to be related to one another.
Hierarchical model
The hierarchical model is similar to the network model except that links in the hierarchical model form a tree structure,while the network model allows arbitrary graph.
Network model
This model organizes data using two fundamental constructs, called records and sets. Records contain fields, and sets define one-to-many relationships between records: one owner, many members.The network data model is an abstraction of the design concept used in the implementation of databases.
Relational model
is a database model based on first-order predicate logic. Its core idea is to describe a database as a collection of predicates over a finite set of predicate variables, describing constraints on the possible values and combinations of values.The power of the relational data model lies in its mathematical foundations and a simple user-level paradigm.
Object-relational model
Similar to a relational database model, but objects, classes and inheritance are directly supported in database schemas and in the query language.
Star schema
The simplest style of data warehouse schema. The star schema consists of a few "fact tables" (possibly only one, justifying the name) referencing any number of "dimension tables". The star schema is considered an important special case of the snowflake schema.
Flat model
Hierarchical model
Network model
Relational model
Concept-oriented model
Star schema
Data structure diagram[edit]
Main article: Data structure diagram
Example of a Data Structure Diagram
A data structure diagram (DSD) is a diagram and data model used to describe conceptual data models by providing graphical notations which document entities and their relationships, and the constraints that bind them. The basic graphic elements of DSDs are boxes, representing entities, and arrows, representing relationships. Data structure diagrams are most useful for documenting complex data entities.
Data structure diagrams are an extension of the entity-relationship model (ER model). In DSDs, attributes are specified inside the entity boxes rather than outside of them, while relationships are drawn as boxes composed of attributes which specify the constraints that bind entities together. The E-R model, while robust, doesn't provide a way to specify the constraints between relationships, and becomes visually cumbersome when representing entities with several attributes. DSDs differ from the ER model in that the ER model focuses on the relationships between different entities, whereas DSDs focus on the relationships of the elements within an entity and enable users to fully see the links and relationships between each entity.
There are several styles for representing data structure diagrams, with the notable difference in the manner of defining cardinality. The choices are between arrow heads, inverted arrow heads (crow's feet), or numerical representation of the cardinality.
Example of an IDEF1X Entity relationship diagrams used to model IDEF1X itself[16]
Entity-relationship model[edit]
Main article: Entity-relationship model
An entity-relationship model (ERM), sometimes referred to as an entity-relationship diagram (ERD), is an abstract conceptual data model (or semantic data model) used in software engineering to represent structured data. There are several notations used for ERMs.
Geographic data model[edit]
Main article: Data model (GIS)
A data model in Geographic information systems is a mathematical construct for representing geographic objects or surfaces as data. For example,
the vector data model represents geography as collections of points, lines, and polygons;
the raster data model represent geography as cell matrixes that store numeric values;
and the Triangulated irregular network (TIN) data model represents geography as sets of contiguous, nonoverlapping triangles.[17]
Groups relate to process of making a map[18]
NGMDB data model applications[18]
NGMDB databases linked together[18]
Representing 3D map information[18]
Generic data model[edit]
Main article: Generic data model
Generic data models are generalizations of conventional data models. They define standardised general relation types, together with the kinds of things that may be related by such a relation type. Generic data models are developed as an approach to solve some shortcomings of conventional data models. For example, different modelers usually produce different conventional data models of the same domain. This can lead to difficulty in bringing the models of different people together and is an obstacle for data exchange and data integration. Invariably, however, this difference is attributable to different levels of abstraction in the models and differences in the kinds of facts that can be instantiated (the semantic expression capabilities of the models). The modelers need to communicate and agree on certain elements which are to be rendered more concretely, in order to make the differences less significant.
Semantic data model[edit]
Main article: Semantic data model
Semantic data models[16]
A semantic data model in software engineering is a technique to define the meaning of data within the context of its interrelationships with other data. A semantic data model is an abstraction which defines how the stored symbols relate to the real world.[16] A semantic data model is sometimes called a conceptual data model.
The logical data structure of a database management system (DBMS), whether hierarchical, network, or relational, cannot totally satisfy the requirements for a conceptual definition of data because it is limited in scope and biased toward the implementation strategy employed by the DBMS. Therefore, the need to define data from a conceptual view has led to the development of semantic data modeling techniques. That is, techniques to define the meaning of data within the context of its interrelationships with other data. As illustrated in the figure. The real world, in terms of resources, ideas, events, etc., are symbolically defined within physical data stores. A semantic data model is an abstraction which defines how the stored symbols relate to the real world. Thus, the model must be a true representation of the real world.[16]
Data model topics[edit]
Data architecture[edit]
Main article: Data architecture
Data architecture is the design of data for use in defining the target state and the subsequent planning needed to hit the target state. It is usually one of several architecture domains that form the pillars of an enterprise architecture or solution architecture.
A data architecture describes the data structures used by a business and/or its applications. There are descriptions of data in storage and data in motion; descriptions of data stores, data groups and data items; and mappings of those data artifacts to data qualities, applications, locations etc.
Essential to realizing the target state, Data architecture describes how data is processed, stored, and utilized in a given system. It provides criteria for data processing operations that make it possible to design data flows and also control the flow of data in the system.
Data modeling[edit]
Main article: Data modeling
The data modeling process
Data modeling in software engineering is the process of creating a data model by applying formal data model descriptions using data modeling techniques. Data modeling is a technique for defining business requirements for a database. It is sometimes called database modeling because a data model is eventually implemented in a database.[19]
The figure illustrates the way data models are developed and used today. A conceptual data model is developed based on the data requirements for the application that is being developed, perhaps in the context of an activity model. The data model will normally consist of entity types, attributes, relationships, integrity rules, and the definitions of those objects. This is then used as the start point for interface or database design.[8]
Data properties[edit]
Some important properties of data for which requirements need to be met are:
definition-related properties[8]
relevance: the usefulness of the data in the context of your business.
clarity: the availability of a clear and shared definition for the data.
consistency: the compatibility of the same type of data from different sources.
Some important properties of data[8]
content-related properties
timeliness: the availability of data at the time required and how up to date that data is.
accuracy: how close to the truth the data is.
properties related to both definition and content
completeness: how much of the required data is available.
accessibility: where, how, and to whom the data is available or not available (e.g. security).
cost: the cost incurred in obtaining the data, and making it available for use.
Data organization[edit]
Another kind of data model describes how to organize data using a database management system or other data management technology. It describes, for example, relational tables and columns or object-oriented classes and attributes. Such a data model is sometimes referred to as the physical data model, but in the original ANSI three schema architecture, it is called "logical". In that architecture, the physical model describes the storage media (cylinders, tracks, and tablespaces). Ideally, this model is derived from the more conceptual data model described above. It may differ, however, to account for constraints like processing capacity and usage patterns.
While data analysis is a common term for data modeling, the activity actually has more in common with the ideas and methods of synthesis (inferring general concepts from particular instances) than it does with analysis (identifying component concepts from more general ones). {Presumably we call ourselves systems analysts because no one can say systems synthesists.} Data modeling strives to bring the data structures of interest together into a cohesive, inseparable, whole by eliminating unnecessary data redundancies and by relating data structures with relationships.
A different approach is to use adaptive systems such as artificial neural networks that can autonomously create implicit models of data.
Data structure[edit]
Main article: Data structure
A binary tree, a simple type of branching linked data structure
A data structure is a way of storing data in a computer so that it can be used efficiently. It is an organization of mathematical and logical concepts of data. Often a carefully chosen data structure will allow the most efficient algorithm to be used. The choice of the data structure often begins from the choice of an abstract data type.
A data model describes the structure of the data within a given domain and, by implication, the underlying structure of that domain itself. This means that a data model in fact specifies a dedicated grammar for a dedicated artificial language for that domain. A data model represents classes of entities (kinds of things) about which a company wishes to hold information, the attributes of that information, and relationships among those entities and (often implicit) relationships among those attributes. The model describes the organization of the data to some extent irrespective of how data might be represented in a computer system.
The entities represented by a data model can be the tangible entities, but models that include such concrete entity classes tend to change over time. Robust data models often identify abstractions of such entities. For example, a data model might include an entity class called "Person", representing all the people who interact with an organization. Such an abstract entity class is typically more appropriate than ones called "Vendor" or "Employee", which identify specific roles played by those people.
Array
Hash table
Linked list
Stack (data structure)
Data model theory[edit]
The term data model can have two meanings:[20]
A data model theory, i.e. a formal description of how data may be structured and accessed.
A data model instance, i.e. applying a data model theory to create a practical data model instance for some particular application.
A data model theory has three main components:[20]
The structural part: a collection of data structures which are used to create databases representing the entities or objects modeled by the database.
The integrity part: a collection of rules governing the constraints placed on these data structures to ensure structural integrity.
The manipulation part: a collection of operators which can be applied to the data structures, to update and query the data contained in the database.
For example, in the relational model, the structural part is based on a modified concept of the mathematical relation; the integrity part is expressed in first-order logic and the manipulation part is expressed using the relational algebra, tuple calculus and domain calculus.
A data model instance is created by applying a data model theory. This is typically done to solve some business enterprise requirement. Business requirements are normally captured by a semantic logical data model. This is transformed into a physical data model instance from which is generated a physical database. For example, a data modeler may use a data modeling tool to create an entity-relationship model of the corporate data repository of some business enterprise. This model is transformed into a relational model, which in turn generates a relational database.
Patterns[edit]
Patterns[21] are common data modeling structures that occur in many data models.
Related models[edit]
Data flow diagram[edit]
Main article: Data flow diagram
Data Flow Diagram example[22]
A data flow diagram (DFD) is a graphical representation of the "flow" of data through an information system. It differs from the flowchart as it shows the data flow instead of the control flow of the program. A data flow diagram can also be used for the visualization of data processing (structured design). Data flow diagrams were invented by Larry Constantine, the original developer of structured design,[23] based on Martin and Estrin's "data flow graph" model of computation.
It is common practice to draw a context-level Data flow diagram first which shows the interaction between the system and outside entities. The DFD is designed to show how a system is divided into smaller portions and to highlight the flow of data between those parts. This context-level Data flow diagram is then "exploded" to show more detail of the system being modeled
Information model[edit]
Main article: Information model
Example of an EXPRESS G Information model
An Information model is not a type of data model, but more or less an alternative model. Within the field of software engineering both a data model and an information model can be abstract, formal representations of entity types that includes their properties, relationships and the operations that can be performed on them. The entity types in the model may be kinds of real-world objects, such as devices in a network, or they may themselves be abstract, such as for the entities used in a billing system. Typically, they are used to model a constrained domain that can be described by a closed set of entity types, properties, relationships and operations.
According to Lee (1999)[24] an information model is a representation of concepts, relationships, constraints, rules, and operations to specify data semantics for a chosen domain of discourse. It can provide sharable, stable, and organized structure of information requirements for the domain context.[24] More in general the term information model is used for models of individual things, such as facilities, buildings, process plants, etc. In those cases the concept is specialised to Facility Information Model, Building Information Model, Plant Information Model, etc. Such an information model is an integration of a model of the facility with the data and documents about the facility.
An information model provides formalism to the description of a problem domain without constraining how that description is mapped to an actual implementation in software. There may be many mappings of the information model. Such mappings are called data models, irrespective of whether they are object models (e.g. using UML), entity relationship models or XML schemas.
Document Object Model, a standard object model for representing HTML or XML
Object model[edit]
Main article: Object model
An object model in computer science is a collection of objects or classes through which a program can examine and manipulate some specific parts of its world. In other words, the object-oriented interface to some service or system. Such an interface is said to be the object model of the represented service or system. For example, the Document Object Model (DOM) [1] is a collection of objects that represent a page in a web browser, used by script programs to examine and dynamically change the page. There is a Microsoft Excel object model[25] for controlling Microsoft Excel from another program, and the ASCOM Telescope Driver[26] is an object model for controlling an astronomical telescope.
In computing the term object model has a distinct second meaning of the general properties of objects in a specific computer programming language, technology, notation or methodology that uses them. For example, the Java object model, the COM object model, or the object model of OMT. Such object models are usually defined using concepts such as class, message, inheritance, polymorphism, and encapsulation. There is an extensive literature on formalized object models as a subset of the formal semantics of programming languages.
Object-Role Model[edit]
Main article: Object-Role Modeling
Example of the application of Object-Role Modeling in a "Schema for Geologic Surface", Stephen M. Richard (1999)[27]
Object-Role Modeling (ORM) is a method for conceptual modeling, and can be used as a tool for information and rules analysis.[28]
Object-Role Modeling is a fact-oriented method for performing systems analysis at the conceptual level. The quality of a database application depends critically on its design. To help ensure correctness, clarity, adaptability and productivity, information systems are best specified first at the conceptual level, using concepts and language that people can readily understand.
The conceptual design may include data, process and behavioral perspectives, and the actual DBMS used to implement the design might be based on one of many logical data models (relational, hierarchic, network, object-oriented etc.).[29]
Unified Modeling Language models[edit]
Main article: Unified Modeling Language
The Unified Modeling Language (UML) is a standardized general-purpose modeling language in the field of software engineering. It is a graphical language for visualizing, specifying, constructing, and documenting the artifacts of a software-intensive system. The Unified Modeling Language offers a standard way to write a system's blueprints, including:[30]
Conceptual things such as business processes and system functions
Concrete things such as programming language statements, database schemas, and
Reusable software components.
UML offers a mix of functional models, data models, and database models.
See also[edit]
Business process model
Core Architecture Data Model
Data dictionary
JC3IEDM
Process model
Data Format Description Language (DFDL)
Structured Search
Data collection system
Key-objects
References[edit]
Jump up ^ "datamodel - UML Domain Modeling - Stack Overflow". Stack Overflow. Stack Exchange Inc. Retrieved 4 February 2017.
Jump up ^ "XQuery and XPath Data Model 3.1". World Wide Web Consortium (W3C). W3C. Retrieved 4 February 2017.
Jump up ^ "datamodel". npm. npm, Inc. Retrieved 4 February 2017.
Jump up ^ "DataModel (Java EE 6)". Java Documentation. Oracle. Retrieved 4 February 2017.
Jump up ^ Ostrovskiy, Stan. "iOS: Three ways to pass data from Model to Controller". Medium. A Medium Corporation. Retrieved 4 February 2017.
Jump up ^ Paul R. Smith & Richard Sarfaty Publications, LLC 2009
Jump up ^ Michael R. McCaleb (1999). "A Conceptual Data Model of Datum Systems". National Institute of Standards and Technology. August 1999.
^ Jump up to: a b c d e f g h i j k Matthew West and Julian Fowler (1999). Developing High Quality Data Models. The European Process Industries STEP Technical Liaison Executive (EPISTLE).
Jump up ^ American National Standards Institute. 1975. ANSI/X3/SPARC Study Group on Data Base Management Systems; Interim Report. FDT (Bulletin of ACM SIGMOD) 7:2.
Jump up ^ Young, J. W., and Kent, H. K. (1958). "Abstract Formulation of Data Processing Problems". In: Journal of Industrial Engineering. Nov-Dec 1958. 9(6), pp. 471-479
^ Jump up to: a b Janis A. Bubenko jr (2007) "From Information Algebra to Enterprise Modelling and Ontologies - a Historical Perspective on Modelling for Information Systems". In: Conceptual Modelling in Information Systems Engineering. John Krogstie et al. eds. pp 1-18
Jump up ^ Cornelius T. Leondes (2002). Database and Data Communication Network Systems: Techniques and Applications. Page 7
Jump up ^ "Derivability, Redundancy, and Consistency of Relations Stored in Large Data Banks", E.F. Codd, IBM Research Report, 1969
Jump up ^ Data and Reality
Jump up ^ Jan L. Harrington (2000). Object-oriented Database Design Clearly Explained. p.4
^ Jump up to: a b c d FIPS Publication 184 released of IDEF1X by the Computer Systems Laboratory of the National Institute of Standards and Technology (NIST). 21 December 1993 (withdrawn in 2008).
Jump up ^ Wade, T. and Sommer, S. eds. A to Z GIS
^ Jump up to: a b c d David R. Soller1 and Thomas M. Berg (2003). The National Geologic Map Database Project: Overview and Progress U.S. Geological Survey Open-File Report 03–471.
Jump up ^ Whitten, Jeffrey L.; Lonnie D. Bentley, Kevin C. Dittman. (2004). Systems Analysis and Design Methods. 6th edition. ISBN 0-256-19906-X.
^ Jump up to: a b Beynon-Davies P. (2004). Database Systems 3rd Edition. Palgrave, Basingstoke, UK. ISBN 1-4039-1601-2
Jump up ^ "The Data Model Resource Book: Universal Patterns for Data Modeling" Len Silverstone & Paul Agnew (2008).
Jump up ^ John Azzolini (2000). Introduction to Systems Engineering Practices. July 2000.
Jump up ^ W. Stevens, G. Myers, L. Constantine, "Structured Design", IBM Systems Journal, 13 (2), 115-139, 1974.
^ Jump up to: a b Y. Tina Lee (1999). "Information modeling from design to implementation" National Institute of Standards and Technology.
Jump up ^ Excel Object Model Overview
Jump up ^ "ASCOM General Requirements". 2011-05-13. Retrieved 2014-09-25.
Jump up ^ Stephen M. Richard (1999). Geologic Concept Modeling. U.S. Geological Survey Open-File Report 99-386.
Jump up ^ Joachim Rossberg and Rickard Redler (2005). Pro Scalable .NET 2.0 Application Designs.. Page 27
Jump up ^ Object Role Modeling: An Overview (msdn.microsoft.com). Retrieved 19 September 2008.
Jump up ^ Grady Booch, Ivar Jacobson & Jim Rumbaugh (2000) OMG Unified Modeling Language Specification, Version 1.4 (2002).
Further reading[edit]
David C. Hay (1996). Data Model Patterns: Conventions of Thought. New York:Dorset House Publishers, Inc.
Len Silverston (2001). The Data Model Resource Book Volume 1/2. John Wiley & Sons.
Len Silverston & Paul Agnew (2008). The Data Model Resource Book: Universal Patterns for data Modeling Volume 3. John Wiley & Sons.
Matthew West and Julian Fowler (1999). Developing High Quality Data Models. The European Process Industries STEP Technical Liaison Executive (EPISTLE).
Matthew West (2011) Developing High Quality Data Models Morgan Kaufmann
[show]
v
t
e
Data model
Main
Architecture
Modeling
Structure
Schemas
Conceptual
Logical
Physical
Types
Database
Data structure diagram
Entity–relationship model (enhanced)
Geographic
Generic
Semantic
Related models
Data flow diagram
Information model
Object model
Object-role modeling
Unified Modeling Language
See also
Database design
Business process modeling
Core architecture data model
Enterprise modelling
Function model
Process modeling
XML schema
Data Format Description Language
[show]
v
t
e
Software engineering
Fields
Computer programming
Requirements engineering
Software deployment
Software design
Software maintenance
Software testing
Systems analysis
Formal methods
Concepts
Data modeling
Enterprise architecture
Functional specification
Modeling language
Orthogonality
Programming paradigm
Software
Software archaeology
Software architecture
Software configuration management
Software development methodology
Software development process
Software quality
Software quality assurance
Software verification and validation
Structured analysis
Orientations
Agile
Aspect-oriented
Object orientation
Ontology
Service orientation
SDLC
Models
Developmental
Agile
EUP
Executable UML
Incremental model
Iterative model
Prototype model
RAD
UP
Scrum
Spiral model
V-Model
Waterfall model
XP
Other
SPICE
CMMI
Data model
ER model
Function model
Information model
Metamodeling
Object model
Systems model
View model
Languages
IDEF
UML
USL
SysML
Software
engineers
Victor Basili
Kent Beck
Grady Booch
Fred Brooks
Barry Boehm
Peter Chen
Danese Cooper
Ward Cunningham
Tom DeMarco
Edsger W. Dijkstra
Delores M. Etter
Martin Fowler
Adele Goldstine
Margaret Hamilton
C. A. R. Hoare
Lois Haibt
Mary Jean Harrold
Grace Hopper
Watts Humphrey
Michael A. Jackson
Ivar Jacobson
Alan Kay
Nancy Leveson
Stephen J. Mellor
Bertrand Meyer
David Parnas
Trygve Reenskaug
Winston W. Royce
James Rumbaugh
Mary Shaw
Peri Tarr
Elaine Weyuker
Niklaus Wirth
Edward Yourdon
Nuno Silva
Related fields
Computer science
Computer engineering
Project management
Risk management
Systems engineering
Category
Commons
Retrieved from "https://en.wikipedia.org/w/index.php?title=Data_model&oldid=802919300"
Categories:
Data modeling
Navigation menu
Personal tools
Not logged in
Talk
Contributions
Create account
Log in
Namespaces
Article
Talk
Variants
Views
Read
Edit
View history
More
Search
Navigation
Main page
Contents
Featured content
Current events
Random article
Donate to Wikipedia
Wikipedia store
Interaction
Help
About Wikipedia
Community portal
Recent changes
Contact page
Tools
What links here
Related changes
Upload file
Special pages
Permanent link
Page information
Wikidata item
Cite this page
Print/export
Create a book
Download as PDF
Printable version
In other projects
Wikimedia Commons
Languages
العربية
Azərbaycanca
Deutsch
Ελληνικά
Español
فارسی
Français
한국어
Italiano
Қазақша
Nederlands
日本語
Norsk
Русский
தமிழ்
ไทย
Українська
中文
Edit links
This page was last edited on 29 September 2017, at 08:56.
Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.
Privacy policy
About Wikipedia
Disclaimers
Contact Wikipedia
Developers
Cookie statement
Mobile view

key: html

type: local

value: div

attrs: id class

values: mw-page-base noprint

values: mw-head-base noprint

attrs: id class style

value: a

attrs: id class lang

values: firstHeading firstHeading en

values: siteSub noprint

values: jump-to-nav mw-jump

value: sup

attrs: href title

value: p

attrs: alt src width height class srcset data-file-width data-file-height

values:
/wiki/Software_code
mw-redirect
Software code

values:
/wiki/Computer_software
mw-redirect
Computer software

values:
/wiki/Enterprise_model
mw-redirect
Enterprise model

values:
/wiki/Three_schema_approach
mw-redirect
Three schema approach

values:
/wiki/Conceptual_data_model
mw-redirect
Conceptual data model

values:
/wiki/Database_system
mw-redirect
Database system

values:
/wiki/Network_data_model
mw-redirect
Network data model

values:
/wiki/Hierarchical_data_model
mw-redirect
Hierarchical data model

values:
/wiki/Entity_relationship_model
mw-redirect
Entity relationship model

values:
/wiki/Ontology_(computer_science)
mw-redirect
Ontology (computer science)

values:
/wiki/Universe_of_discourse
mw-redirect
Universe of discourse

values:
/wiki/Object-Role_Modeling
mw-redirect
Object-Role Modeling

values:
/wiki/Hierarchical_model
mw-redirect
Hierarchical model

values:
/wiki/Object-relational_model
mw-redirect
Object-relational model

attrs: alt src width height srcset data-file-width data-file-height

values:
/wiki/Entity_class
mw-redirect
Entity class

values:
/wiki/Integrity_constraints
mw-redirect
Integrity constraints

values:
/wiki/Entity-relationship_model
mw-redirect
Entity-relationship model

values:
/wiki/Database_management_system
mw-redirect
Database management system

values:
/wiki/Abstract_entity
mw-redirect
Abstract entity

values:
/wiki/Stack_(data_structure)
mw-redirect
Stack (data structure)

values:
/wiki/Relation_(mathematics)
mw-redirect
Relation (mathematics)

values:
/wiki/Tuple_calculus
mw-redirect
Tuple calculus

values:
/wiki/Domain_calculus
mw-redirect
Domain calculus

values:
/wiki/System_Context_Diagram
mw-redirect
System Context Diagram

values:
/wiki/Facility_Information_Model
mw-redirect
Facility Information Model

values:
nofollow
http://www.w3.org/DOM/
external autonumber

values:
/wiki/Class_(computer_science)
mw-redirect
Class (computer science)

values:
/wiki/Message_(computer_science)
mw-redirect
Message (computer science)

values:
/wiki/Inheritance_(computer_science)
mw-redirect
Inheritance (computer science)

values: Polymorphism in object-oriented programming

values: Formal semantics of programming languages

values:
/wiki/Conceptual_modeling
mw-redirect
Conceptual modeling

values: Edit section: Unified Modeling Language models

values:
/wiki/Functional_model
mw-redirect
Functional model

values:
/wiki/Business_process_model
mw-redirect
Business process model

values:
/wiki/Core_Architecture_Data_Model
mw-redirect
Core Architecture Data Model

values:
/wiki/Process_model
mw-redirect
Process model

values:
nofollow
external text
http://stackoverflow.com/a/3835214

values:
nofollow
external text
https://www.npmjs.com/package/datamodel

values:
/wiki/Janis_A._Bubenko_jr
mw-redirect
Janis A. Bubenko jr

values:
nofollow
external text
http://www.bkent.net/Doc/darxrp.htm

values:
/wiki/Whitten,_Jeffrey_L.
mw-redirect
Whitten, Jeffrey L.

values:
nofollow
external text
http://acsdb.com/ref/uml14.pdf

values: -moz-column-width: 30em; -webkit-column-width: 30em; column-width: 30em; list-style-type: decimal;

values:
/wiki/Physical_schema
mw-redirect
Physical schema

values: nowraplinks collapsible autocollapse navbox-inner

attrs: alt src title width height srcset data-file-width data-file-height

values: nowraplinks hlist collapsible autocollapse navbox-inner

values:
catlinks mw-normal-catlinks
catlinks mw-normal-catlinks
interface

values: Discussion about edits from this IP address [ctrl-alt-n]

values: A list of edits made from this IP address [ctrl-alt-y]

values: You are encouraged to create an account and log in; however, it is not mandatory

values: You're encouraged to log in; however, it's not mandatory. [ctrl-alt-o]

values:
/wiki/Data_model
View the content page [ctrl-alt-c]
c

values: Discussion about the content page [ctrl-alt-t]

values: p-namespaces navigation vectorTabs p-namespaces-label

values:
p-variants
navigation
vectorMenu emptyPortlet
p-variants-label

values: Past revisions of this page [ctrl-alt-h]

values: p-views navigation vectorTabs p-views-label

values:
p-cactions
navigation
vectorMenu emptyPortlet
p-cactions-label

values:
mw-wiki-logo
/wiki/Main_Page
Visit the main page

values:
/wiki/Main_Page
Visit the main page [ctrl-alt-z]
z

values: Featured content – the best of Wikipedia

values: Find background information on current events

values:
/wiki/Special:Random
Load a random article [ctrl-alt-x]
x

values: portal navigation p-navigation p-navigation-label

values: Guidance on how to use and edit Wikipedia

values: About the project, what you can do, where to find things

values: A list of recent changes in the wiki [ctrl-alt-r]

values: portal navigation p-interaction p-interaction-label

values: List of all English Wikipedia pages containing links to this page [ctrl-alt-j]

values: Recent changes in pages linked from this page [ctrl-alt-k]

values:
/wiki/Wikipedia:File_Upload_Wizard
Upload files [ctrl-alt-u]
u

values: A list of all special pages [ctrl-alt-q]

values: Permanent link to this revision of the page

values: Link to connected data repository item [ctrl-alt-g]

values: Printable version of this page [ctrl-alt-p]

values: portal navigation p-wikibase-otherprojects p-wikibase-otherprojects-label

values:
uls-settings-trigger
Language settings
0
button
true

values: نماذج بيانات – Arabic

values: Μοντέλο δεδομένων – Greek

values: مدل داده – Persian

values: 데이터 모델 – Korean

values: Мәліметтер моделі – Kazakh

values:
https://nl.wikipedia.org/wiki/Datamodel
Datamodel – Dutch
nl
nl
interlanguage-link-target

values: Модель данных – Russian

values: தரவு மாதிரி – Tamil

values: แบบจำลองข้อมูล – Thai

values: Модель даних – Ukrainian

values:
suggestions
display: none; font-size: 13px;

values: mediawiki ltr sitedir-ltr mw-hide-empty-elt ns-0 ns-subject page-Data_model rootpage-Data_model vector-nav-directionality skin-vector action-view