The Old Testament (sometimes abbreviated as OT) is the first section of the two-part Christian Biblical canon.
Most scholars agree that the Old Testament was composed and compiled between the 12th and the 2nd century BC. The books of the Old Testament were therefore completed before Jesus' birth. Jesus and his disciples based their teachings on them, referring to them as "the law of Moses, the prophets, and the psalms ... the scriptures". (The accounts of Jesus and his disciples are recorded in the Christian New Testament.)
The exact canon of the Old Testament differs between the various branches of Christianity. All include the books of the Hebrew Bible, while many traditions also recognise several deuterocanonical books.
The Protestant Old Testament is, for the most part, identical with the Hebrew Bible; the differences are minor, dealing only with the arrangement and number of the books. For example, while the Hebrew Bible considers Kings to be a unified text, and Ezra and Nehemiah as a single book, the Protestant Old Testament divides each of these into two books.
The differences between the Hebrew Bible and other versions of the Old Testament such as the Samaritan Pentateuch, the Syriac, Latin, Greek and other canons, are greater. Many of these canons include whole books and additional sections of books that the others do not. The translations of various words from the original Hebrew may also give rise to significant differences of interpretation.