The Old Testament is the collection of books that forms the first of the two-part Christian Biblical canon. The contents of the Old Testment canon vary from church to church, with the Orthodox communion having 51 books: the shared books are those of the shortest canon, that of the major Protestant communions, with 39 books.
All Old Testament canons are related to the Jewish Bible Canon (Tanakh), but with variations. The most important of these variations is a change to the order of the books: the Hebrew Bible ends with the Book of Chronicles, which describes Israel restored to the Promised Land and the Temple restored in Jerusalem; in the Hebrew Bible God's purpose is thus fulfilled and the divine history is at an end, according to Dispensationalism. In the Christian Old Testament the Book of Malachi is placed last, so that a prophesy of the coming of the Messiah leads into the birth of the Christ in the Gospel of Matthew.
The Tanakh is written in Biblical Hebrew and Biblical Aramaic, and is therefore also known as the Hebrew Bible (the text of the Jewish Bible is called the Masoretic, after the medieval Jewish rabbis who compiled it). The Masoretic Text (i.e. the Hebrew text revered by medieval and modern Jews) is only one of several versions of the original scriptures of ancient Judaism, and no manuscripts of that hypothetical original text exist. In the last few centuries before Christ Jewish scholars produced a translation of their scriptures in Greek, the common language of the Eastern portion of the Roman Empire since the conquests of Alexander the Great. This translation, known as the Septuagint, forms the basis of the Orthodox and some other Eastern Old Testaments. The Old Testaments of the Western branches of Christianity were originally based on a Latin translation of the Septuagint known as the Vetus Latina, this was replaced by Jerome's Vulgate, which continues to be highly respected in the Catholic Church, but Protestant churches generally follow translations of a scholarly reference known as the Biblia Hebraica Stuttgartensia. In 1943, Pope Pius XII issued the Divino Afflante Spiritu which allows Catholic translations from texts other than the Vulgate, notably in English the New American Bible.
The Hebrew Bible divides its books into three categories, the Torah ("Instructions"), the Nevi'im ("Prophets") (according to some Christians, essentially historical, despite the title), and the Ketuvim ("Writings}," which according to some Christians might better be described as "wisdom" books (the Song of Songs, Lamentations, Proverbs, etc). The Christian Old Testaments ignore this division and instead emphasise the historical and prophetic nature of the canon - this the Book of Ruth and the Book of Job, part of the Writings in the Hebrew Bible, are reclassified in the Christian canon as history books, and the overall division into Instructions, Prophets and Writings is lost. The reason for this is the over-arching Messianic intention of Christianity - the Old Testament is seen as preparation for the New Testament, and not as a revelation complete in its own right, see Supersessionism for details.
Although it is not a history book in the modern sense, the Old Testament is the primary source for the History of ancient Israel and Judah. The Bible historians presented a picture of ancient Israel based on information that they viewed as historically true. Of particular interest in this regard are the books of Joshua through Second Chronicles.[1][2]
The oldest material in the Hebrew Bible - and therefore in the Christian Old Testament - may date from the 12th century BCE. This material is found embedded within the books of the current Hebrew Bible/Old Testament, which reached their current form at various points between the 5th century BCE (the first five books, the Torah) and the 2nd century BCE[3], see Development of the Jewish Bible canon for details.