The documentary hypothesis (DH) is a model used by biblical scholars to explain the origins and composition of the Torah, the first five books of the Bible (Genesis, Exodus, Leviticus, Numbers, and Deuteronomy).[1] Others are the supplementary hypothesis and the fragmentary hypothesis; all agree that the Torah is not a unified work from a single author, but is made up of sources combined over many centuries by many hands.[2] They differ on the nature of these sources and how they were combined. According to the documentary hypothesis there were four sources, each originally a separate and independent book (a "document"), joined together at various points in time by a series of editors ("redactors").[3] Fragmentary hypotheses see the Torah as a collection of small fragments, and supplementary hypotheses as a single core document supplemented by fragments taken from many sources.[4]