The Hebrew alphabet, known variously by scholars as the Jewish script, square script, block script, is used in the writing of the Hebrew language, as well as other Jewish languages, most notably Yiddish, Ladino, and Judeo-Arabic. There have been two script forms in use; the original old Hebrew script is known as the paleo-Hebrew script (which has been largely preserved, in an altered form, in the Samaritan script), while the present "square" form of the Hebrew alphabet is a stylized form of the Assyrian script. Various "styles" (in current terms, "fonts") of representation of the letters exist. There is also a cursive Hebrew script, which has also varied over time and place.
The Hebrew alphabet has 22 letters, of which five have different forms when used at the end of a word. Hebrew is written from right to left. Originally, the alphabet was an abjad consisting only of consonants. Like other abjads, such as the Arabic alphabet, means were later devised to indicate vowels by separate vowel points, known in Hebrew as niqqud. In rabbinic Hebrew, the letters א ה ו י are also used as matres lectionis to represent vowels. When used to write Yiddish, the writing system is a true alphabet (except for borrowed Hebrew words). In modern usage of the alphabet, as in the case of Yiddish (except that ע replaces ה) and to some extent modern Israeli Hebrew, vowels may be indicated. Today, the trend is toward full spelling with these letters acting as true vowels.
According to contemporary scholars, the original Hebrew script developed during the late second and first millennia BCE alongside others used in the region. It is closely related to the Phoenician script, which was also an abjad, and which itself probably gave rise to the use of alphabetic writing in Greece (Greek alphabet). A distinct Hebrew variant, called the paleo-Hebrew alphabet, emerged by the 10th century BCE, an example of which is represented in the Gezer calendar.
The paleo-Hebrew alphabet was commonly used in the ancient Israelite kingdoms of Israel and Judah, as well as by the Samaritans. Following the exile of the Kingdom of Judah in the 6th century BCE, in the Babylonian exile, Jews began using a form of the Assyrian script, which was another offshoot of the same family of scripts. During the 3rd century BCE, Jews began to use a stylized, "square" form of the Aramaic alphabet that was used by the Persian Empire (which in turn was adopted from the Assyrians), while the Samaritans continued to use a form of the paleo-Hebrew script, called the Samaritan script. After the fall of the Persian Empire, Jews used both scripts before settling on the Assyrian form. For a limited time thereafter, the use of the paleo-Hebrew script among Jews was retained only to write the Tetragrammaton, but soon that custom was also abandoned.
The square Hebrew alphabet was later adapted and used for writing languages of the Jewish diaspora – such as Karaim, Judæo-Arabic, Ladino, Yiddish, etc. The Hebrew alphabet continued in use for scholarly writing in Hebrew and came again into everyday use with the rebirth of the Hebrew language as a spoken language in the 18th and 19th centuries, especially in Israel.