Esperanto alphabet

The Esperanto alphabet is the alphabet which is used to write the Esperanto language. It has 28 (twenty-eight) letters.
The Esperanto alphabet is based on the Roman alphabet (which the English alphabet is also based on). Unlike the English alphabet, it does not have the letters "q", "w", "x" or "y", but it has 6 (six) letters that use a diacritic (a special mark above a letter): "ĉ", "ĝ", "ĥ", "ĵ", "ŝ" and "ŭ".
Alternative writings.
Because Esperanto uses letters with diacritics, there was (and sometimes still is) the need to write text in Esperanto even if the special letters are not available.
L. L. Zamenhof, the creator of Esperanto, proposed the so-called "h-system" ("h-sistemo" in Esperanto). Instead of diacritics, the letter "h" is added, with the only exception being "ŭ". For example, "ĝ" becomes "gh", "ĥ" becomes "hh" and "ŭ" becomes "u". Words which appear to have a diacritic but do not actually can be "broken" with a hyphen or an apostrophe. For example, "flughaveno" (airport) becomes "flug-haveno" or "flug'haveno".
Another system used to replace diacritics is the "x-system" ("x-sistemo" in Esperanto). The letter "x" is not used in the Esperanto alphabet, but it can be used to write diacritics. The x-system, unlike the h-system, does not treat ŭ differently from the other letters. For example, "ĝ" becomes "gx", "ĥ" becomes "hx" and "ŭ" becomes "ux". "flughaveno" remains the same, as there is no ambiguity.
Unicode and HTML.
The whole Esperanto alphabet is part of the Latin-3 and Unicode character sets, and it is included in WGL4. 
The code points and HTML entities for the special Esperanto characters in Unicode are:
Criticism.
Some people say that use of the diacritics (the letters ĉ, ĝ, ĥ, ĵ, ŝ, ŭ) makes the language less natural than it would be using only the basic letters of Latin alphabet. The letters ĉ, ĝ, ĥ, ĵ are not used in any other language in the world.
According to some people, the phonetic system of Esperanto is too similar to the Polish dialect of Białystok, home town of Zamenhof.
Several people consider using the Latin alphabet not to be neutral. In fact, many native languages on each continent (except for Antarctica) use the Latin alphabet to write: for example, German (Europe), Swahili (Africa), Vietnamese (Asia), Tahitian (Oceania), Cree (North America) and Apalaí (South America).