The Book of Leviticus is the third book of the Torah and of the Old Testament, also known as the Third Book of Moses. Many hypotheses presented by scholars as to its origins agree that it developed over a long period of time, reaching its present form during the Persian Period, from 538 to 332 BC, although this is disputed.

The Holiness code is used in biblical criticism to refer to Leviticus chapters 17–26, and sometimes passages in other books of the Pentateuch, especially Numbers and Exodus. It is so called due to its highly repeated use of the word holy. Kadash is usually translated as "holy", but originally meant "set apart", with "special", "clean/pure", "whole" and "perfect" as associated meanings. The term Holiness Code was first coined as the Heiligkeitsgesetz by German theologian August Klostermann in 1877. Critical biblical scholars have regarded it as a distinct unit and have noted that the style is noticeably different from the main body of Leviticus. Unlike the remainder of Leviticus, the many laws of the Holiness Code are expressed very closely packed together, and very briefly.