The Greek language is written in the Greek alphabet, developed in classical times (around the 9th century BC) and passed down to the present. In ancient Greece, its letters were also used to represent numbers, called Greek numerals, in analogy with Roman numerals. Its letters are nowadays used for a variety of other purposes: as mathematical symbols, as names of stars, as names of fraternities and sororities, and so forth.
It is believed that the Greek alphabet was brought to Greece via Phoenician traders. Greek is derived from a Semitic script, but there is controversy as to which one, with both Proto-Canaanite and Phoenician as possibilities. Other theories include as its sources Egypt, Assyria, and Minoan Crete or even many different languages and nations (Polygenetic theory).
Because Greek minuscules are from a (much) later date, no historic minuscule actually exists for San. Minuscule forms for the other letters were only used numerically.
But for number 6 modern Greeks use an old digraph called stigma (Ϛ, ϛ) instead of digamma or use στ if it is not available. For 90 they use modern z-shaped qoppa forms (Ϟ, ϟ).
The Greek letters and their derivations are as follows (pronunciations transcribed according to SAMPA):
(1): Letter removed from the alphabet in early times, before the period that is now called "classical".
Letter combinations and diphthongs
Greek in Unicode
There are 2 main blocks of Greek characters in Unicode. The first is "Greek and Coptic" (U+0370 — U+03FF). This block is based on ISO 8859-7 and is sufficient to write Modern Greek. There are also some archaic letters and Greek-based technical symbols.
This block also supports Coptic language, most Coptic letters sharing codepoints with looking-alike Greek letters. For Unicode 4.1, it is planned to disunify Coptic from Greek.
To write polytonic Greek (Old Greek or Katharevousa), one may use combining diacritical marks. However, Unicode also includes a full set of precomposed characters in the "Greek Extended" block (U+1F00 — U+1FFF).
Greek and Coptic
Greek Extended (precomposed polytonic Greek)
The most notable change, compared to its predecessor, the Phoenician alphabet, is the introduction of vowels, without which Greek — unlike Phoenician — would be unintelligible. In fact many alphabets that contain vowels, notably the Roman alphabet and Cyrillic alphabet, are derived ultimately from Greek. (For alphabets with signs solely used to designate vowels not derived from the Greek, see Orkhon script, Ethiopic alphabet, Indic alphabets, and Old Hungarian script.) The first vowels were alpha, epsilon, iota, omicron, and upsilon (copied from waw), modifications of either glides or breathing marks, which were mostly superfluous in Greek. In eastern Greek, which lacked breaths entirely, the letter eta was also used for a long e, and eventually the letter omega was introduced for a long o. Vowels were originally not used in Semitic alphabets, but even in the very old Ugaritic alphabet matres lectionis were used, i.e. consonant signs were used to denote vowels.
The letter san was used at variance with sigma, and by classical times the latter won out, san disappearing from the alphabet. The letters waw (later called digamma) and qoppa disappeared, too, the former only needed for the western dialects and the latter never really needed at all. These lived on in the Ionic numeral system, however, which consisted of writing a series letters with precise numerical values. Sampi (apparently in a rare local glyph form from Ionia) was introduced at the end - to stand for 900. Thousands were written with a mark at the upper left ('A for 1000, etc).
Originally there were several variants of the Greek alphabet, most importantly western (Chalcidian) and eastern (Ionic) Greek; the former gave rise to the Etruscan alphabet and thence to the Roman alphabet. Athens took the Ionic script to be its standard in 403 BC, and shortly thereafter the other versions disappeared. By then Greek was always written left to right, but originally it had been written right to left (with asymmetrical characters flipped), and in-between written either way - or, most likely, boustrophedon, so that the lines alternate direction.
During the Middle ages, the Greek scripts underwent changes paralleling those of the Roman alphabet: while the old forms were retained as a monumental script, uncial and eventually minuscule hands came to dominate. The letter σ is even written ς at the ends of words, paralleling the use of the long and short s at the time. Aristophanes of Byzantium also introduced the process of accenting Greek letters for easier pronunciation.
For extended discussion of problematic Greek letter forms see: Greek Unicode Issues (http://www.tlg.uci.edu/~opoudjis/unicode/unicode.html)
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