Romanization of Greek

Romanization of Greek is a way to write the Greek language (either Ancient or Modern Greek) with the Roman alphabet. That can be done by mapping either letters (called transliteration) or sounds (called transcription. The Greek name Ἰωάννης can be transliterated as "Johannes", which became John in Modern English. In Modern Greek, it is generally written Γιάννης, which transliterates to "Yannis". The masculine Greek word Ἅγιος or Άγιος might variously appear as "Hagiοs", "Agios", "Aghios" or "Ayios", or it might simply be translated as "Holy" or "Saint" in English forms of Greek placenames.
Traditional English renderings of Greek names originated from Roman systems that were established in antiquity. The Roman alphabet was a form of the Cumaean alphabet, which was itself developed from the Euboean script, which used as , as , and variant forms of and that later became L and S. When the Euboean script was used to write the classical Greek alphabet, ⟨κ⟩ was replaced with ⟨c⟩, ⟨αι⟩ and ⟨οι⟩ became ⟨æ⟩ and ⟨œ⟩, and ⟨ει⟩ and ⟨ου⟩ were simplified to ⟨i⟩ (more rarely, corresponding to an earlier pronunciation, to ⟨e⟩) and ⟨u⟩. Aspirated consonants like ⟨θ⟩, ⟨φ⟩, initial-⟨ρ⟩, and ⟨χ⟩ simply wrote out the sound: ⟨th⟩, ⟨ph⟩, ⟨rh⟩, and ⟨ch⟩. Because English orthography has changed so much from the original Greek, modern scholarly transliteration now usually renders ⟨κ⟩ as ⟨k⟩ and the diphthongs ⟨αι, οι, ει, ου⟩ as ⟨ai, oi, ei, ou⟩. Modern scholars also increasingly render ⟨χ⟩ as ⟨kh⟩. Greek sounds greatly changed, and Modern Greek sounds quite different from Ancient Greek. That also has had an influence on the terms used in English and other languages and had led to a number of different romanizations for names and placenames in the 19th and the 20th centuries. The Hellenic Organization for Standardization (ELOT) issued its system in co-operation with the International Organization for Standardization (ISO) in 1983. The system was adopted (with minor modifications) by the United Nations' Fifth Conference on the Standardization of Geographical Names at Montreal in 1987, by the United Kingdom's Permanent Committee on Geographical Names for British Official Use (PCGN) and by the United States' Board on Geographic Names (BGN) in 1996, and by the ISO itself in 1997. Romanization of names for official purposes, as with passports and identity cards, were required to use the ELOT system within Greece until 2011, when a legal decision permitted Greeks to use irregular forms (such as "Demetrios" for ) provided that official identification and documents also list the standard forms (as, for example, "Demetrios OR Dimitrios"). Other romanization systems are the BGN/PCGN's earlier 1962 system and the system employed by the American Library Association and the United States' Library of Congress.