The Greek alphabet is the script that has been used to write the Greek language since the 8th century BC. It was derived from the earlier Phoenician alphabet, and was in turn the ancestor of numerous other European and Middle Eastern scripts, including Cyrillic and Latin. Apart from its use in writing the Greek language, both in its ancient and its modern forms, the Greek alphabet today also serves as a source of technical symbols and labels in many domains of mathematics, science and other fields.
In its classical and modern forms, the alphabet has 24 letters, ordered from alpha to omega. Like Latin and Cyrillic, Greek originally had only a single form of each letter; it developed the letter case distinction between upper-case and lower-case forms in parallel with Latin during the modern era.
Sound values and conventional transcriptions for some of the letters differ between Ancient Greek and Modern Greek usage, owing to phonological changes in the language.
In traditional ("polytonic") Greek orthography, vowel letters can be combined with several diacritics, including accent marks, so-called "breathing" marks, and the iota subscript. In common present-day usage for Modern Greek since the 1980s, this system has been simplified to a so-called "monotonic" convention.