The book of Exodus records two major events in Israel's life as a nation. The first is God's deliverance of Israel out of Egypt. After roughly four hundred years of captivity in Egypt, God's chosen people "exit" through a miraculous and dramatic series of events. The second major event is God's revelation of his Law. God met with Moses on top of Mount Sinai and revealed his designs for this infant nation. In Exodus, we see God redeeming his people and then expressing his desire for how they should live as redeemed and grateful people.
Chapters 1-18 depict Israel's exodus from their bondage in Egypt, while chapters 19-40 record God's instructions regarding their life and worship. Woven throughout these two activities of God we discover Israel grumbling, testing God, and committing idolatry.