Sound values and conventional transcriptions for some of the letters differ between Ancient and Modern Greek usage because the pronunciation of Greek has changed significantly between the 5th century BC and today. Like Latin and Cyrillic, Greek originally had only a single form of each letter it developed the letter case distinction between uppercase and lowercase in parallel with Latin during the modern era. The Greek alphabet is the ancestor of the Latin and Cyrillic scripts. The uppercase and lowercase forms of the 24 letters are: In Archaic and early Classical times, the Greek alphabet existed in many local variants, but, by the end of the 4th century BC, the Euclidean alphabet, with 24 letters, ordered from alpha to omega, had become standard and it is this version that is still used for Greek writing today. It is derived from the earlier Phoenician alphabet, and was the earliest known alphabetic script to have distinct letters for vowels as well as consonants. The Greek alphabet has been used to write the Greek language since the late 9th or early 8th century BC.
