The Hebrew alphabet consists of 22 letters used for writing the Hebrew language. Five of these letters have a different form when appearing as the last letter in a word. The Hebrew letters are also used in mildly adapted forms for writing several languages of the Jewish diaspora, most famously Yiddish, Ladino, and Judeo-Arabic (for a full and detailed list, see Jewish languages). Hebrew is written from right to left.
The Hebrew alphabet is an abjad, having letters only for consonants, but means were later devised to indicate vowels by separate vowel points or niqqud. In rabbinic Hebrew, the consonant letters are used as matres lectionis to represent vowels.
The number of letters in the Hebrew alphabet, their order, their names, and their phonetic values are virtually identical to those of the Aramaic alphabet, as both Hebrews and Arameans borrowed the Phoenician alphabet for their uses during the end of the 2nd millennium BCE.
According to contemporary scholars, the modern script used for writing Hebrew (usually called the Jewish script by scholars, and also traditionally known as the square script, block script, or Assyrian script — not to be confused with the Eastern variant of the Syriac alphabet) evolved during the 3rd century BCE from the Aramaic script, which had been used by Jews for writing Hebrew since the 6th century BCE, retaining the old script only for the Name of God. Prior to that, Hebrew was written using the old Hebrew script, which evolved during the 10th century BCE from the Phoenician script; the Samaritans still write Hebrew in a variant of this script for religious works (see Samaritan alphabet).
According to contemporary scholars, the original Hebrew script developed alongside others in the region during the course of the late second and first millennia BCE; it is closely related to the Phoenician script, which itself probably gave rise to the use of alphabetic writing in Greece (Greek). It is sometimes claimed that around the 10th century BCE a distinct Hebrew variant, the original "Hebrew script", emerged, which was widely used in the ancient kingdoms of Israel and Judah until they fell in the 8th and 6th centuries BCE, respectively. It is not straightforward, however, to distinguish Israelite/Judahite scripts from others which were in use in the immediate area, most notably by the Moabites and Ammonites.
Following the Babylonian exile, Jews gradually stopped using the Hebrew script, and instead adopted the Aramaic script (another offshoot of the same family of scripts). This script, as used for writing Hebrew, later evolved into the Jewish, or "square" script, that is still used today. Closely related scripts were in use all over the Middle East for several hundred years, but following the rise of Christianity (and later, the rise of Islam), they gave way to the hebrew and Arabic alphabets, respectively.
The Hebrew alphabet was later adapted in order to write down the languages of the Jewish diaspora (Karaim, Judæo-Arabic, Ladino, Yiddish, etc.). The Hebrew alphabet was retained as the alphabet used for writing down the Hebrew language during its rebirth in the 18th to 19th century.