(Job is sometimes classed as "Historical" and sometimes as "Wisdom")
The Old Testament comprises Hebrew scriptures from before the time of Christ. It has traditionally been seen as containing three types of material: the Law, the Prophets, and Writings. Jews refer to it collectively as Tenakh, from the initials of the Hebrew names of those three categories: Torah, Neviim, and Ketuvim — perhaps the world's oldest Three Letter Acronym (TLA)!
Some commentators have argued that the Old Testament is based on oral traditions that were written down during the exile, on the assumption that literacy was probably rare until then. However, recent evidence shows that literacy was widespread in Judah before the exile. Clay tablets bearing ink inscriptions in Hebrew were found dating from about 600 BCE:
"The team...examined 16 ink inscriptions on ceramic shards discovered at the site of an ancient military fortress in Arad in southern Israel. The inscriptions themselves are not biblical texts. Instead, they detail troop movements and expenses for provisions, indicating that people throughout the military chain of command down to the fort's deputy quartermaster were able to write. The tone of the inscriptions, which suggest they were not written by professional scribes, combined with the fortress's remote location, indicate a wide spread of literacy at the time, according to the study." 
While it is accepted that the oldest parts of the Bible probably began as oral tradition, recent studies have abandoned the idea that the Old Testament dates from the exile or later. "If one was inventing something, would it really be so disordered and chaotic, so varied in genre and mixed in viewpoint?" 
The sequence of books from Genesis to 2 Kings has a common emphasis, and must predate the return from exile or they would describe it; 1 Chronicles – Nehemiah have a very different emphasis, and must be more recent since they describe the return from exile.[1 p.25] The antiquity of the books up to 2 Kings is not in doubt, since the LXX, Masoretic and Samaritan versions of them represent separate traditions each going back to at least the 3rd century BCE, and all are represented by scrolls from Qumran.[1 p.26] Deuteronomy, Joshua, Judges, Samuel and Kings show a striking unity of language, style and content, and are attributed to a hypothetical "Deuteronomistic Historian" or "circle". (Jesus seems to support the view that Deuteronomy is a late addition to the Torah because in Mark 10:8 he gives text from Genesis priority over Deuteronomy.) Ancient tradition says that the prophet Jeremiah wrote 1 and 2 Kings. Jeremiah prophesied from 627 BCE. The books of Samuel show common ancestry with them, yet signs of compilation from several sources, so perhaps Jeremiah edited the books Deuteronomy to Samuel into their present form.
2 Samuel 9–20 and 1 Kings 1–2 (see Structure above) show a consistent style involving direct speech and well-developed secondary characters, and appear to be a complete literary unit. However, 1 Kings 1–2 go into far more detail than the earlier passages, suggesting that the author lived at that time. Overall, the books are an official version of selected events.[4 p.xxiii–xxxi]
The traditional name "Old Testament" does not derive from the Hebrew Bible itself, but from contrast with the early Christian writings which Christians understand as establishing the "New Covenant" promised in Jeremiah 31:31.[5 pp 196f] Drane describes the Old Testament as being about "the activity of God" which reveals God as "one with whom human beings can — and do — have personal dealings" [6 p.12]. It has been seen as a lived-out allegory[12 p84].
There are no "goodies" or "baddies" in the Old Testament; every hero falls off their pedestal, and every tyrant has godly moments.
See also Professor Walter Moberly's notes.
© David Billin 2002–2019