Leviticus outlines rules and regulations for the Israelites regarding sacrifices, priesthood, cleanliness, daily life, and vows. It establishes a system of sacrifices to build the people's relationship with God and cover sins. It details the beginning of the priestly order with Aaron and his descendants serving as priests. Laws of purity maintained ritual cleanliness in the community and protected against disease and pagan influence. Additional rules governed social and moral conduct. The book emphasizes obedience to God, holiness as God's set-apart people, and the covenant relationship between God and the Israelites.