The origins of the alphabet are unknown, but there are several theories as to how it developed. One popular proposal — the Proto-Sinaitic theory — is that the history of the alphabet began in Ancient Egypt, more than a millennium into the history of writing. Under this theory, the alphabet was invented to represent the language of Semitic workers in Egypt (see Middle Bronze Age alphabets), and was at least influenced by the alphabetic principles of the Egyptian hieratic script. If correct, nearly all alphabets in the world today either descend directly from this development or were inspired by its design.
The most widely used alphabet today is the Latin alphabet. It derives from the Greek, the first true alphabet in that it consistently assigns letters to both consonants and vowels. The Greek alphabet in turn was derived from the Phoenician alphabet, which was an abjad – a system where each symbol usually stands for a consonant. Two scripts are well attested from before the end of the fourth millennium BCE: Mesopotamian cuneiform and Egyptian hieroglyphs. Both were well known in the part of the Middle East that produced the first widely used alphabet, the Phoenician. There are signs that cuneiform was developing alphabetic properties in some of the languages it was adapted for, as was seen again later in the Old Persian cuneiform script, but it now appears these developments were a sideline and not ancestral to the alphabet. The Byblos syllabary has suggestive graphic similarities to both hieratic Egyptian and to the Phoenician alphabet, but as the Byblos syllabary is undeciphered, little can be said about its role, if any, in the history of the alphabet.