The Old Testament (sometimes abbreviated OT) is the first section of the two-part Christian Biblical canon, which includes the books of the Hebrew Bible as well as several Deuterocanonical books. Its exact contents differ in the various Christian denominations.
The Protestant Old Testament is, for the most part, identical with the Hebrew Bible. The differences between the Hebrew Bible and the Protestant Old Testament 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, the Protestant Old Testament divides it into two books. Similarly, Ezra and Nehemiah are considered to be one book in the Hebrew Bible.
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 books and even sections of books that the others do not. For a full discussion of these differences, see Books of the Bible. An important difference, as well, can lie in the translations of various words from the original Hebrew.
Most scholars agree that the Old Testament was composed and compiled between the 11th century BC and the 2nd century BC, though parts of it, such as parts of the Torah and the Song of Deborah (Judges 5), probably date back much earlier. The books of the Old Testament, upon which Jesus and his disciples' deeds and teachings are based, were completed before Jesus' birth. (The accounts of Jesus and his disciples are recorded in the Christian New Testament). The scriptures used by Jesus were, according to Luke 24:44–49, "the law of Moses, and in the prophets, and in the psalms ... the scriptures".