What is the first book of the Old Testament?

The first book of the Old Testament is Genesis because it is the opening book of the Bible in the Christian and Jewish traditions. It is considered the foundational book that explains the creation of the world, the origins of humanity, and the early history of the Hebrew people. Genesis sets the stage for the rest of the Bible by introducing key themes and characters, such as Adam and Eve, Noah and the Flood, Abraham and his covenant with God, and Jacob and his twelve sons who became the twelve tribes of Israel.