The “Yahwist,” according to the documentary hypothesis, is one of four writers whose separate strands were woven together into the Pentateuch. The other trhee are the Elohist, the Priestly Code and the Deuteronomist. Scholars distinguish the strands by such things as style and subject matter. For example, an important distinction between the Yahwist and the Elohist sections is tehri use of the different names for God. For an update on current opinion about this hypothesis, see Joseph Blenkinsopp, “The Documentary Hypothesis in Trouble,” BR 01:04.