Why is the Book of Shemot also called the Book of Exodus?

We usually call the Biblical Books by one of their first words. In particular, this week we started reading the Book of "Names" (Shemot). However, or sages sometimes also called the books of Torah by their alternative names according to their meaning. This book can be also called the Sefer HaGeula - the Book of Redemption, or the Book of "Coming Out" - Exodus.