The Book of Common Prayer is the collection of worship services that all worshipers in an Anglican church follow. It's called "common prayer" because we all pray it together, around the world. The first Book of Common Prayer was compiled in English by Thomas Cranmer in the 16th Century, and since then has undergone many revisions for different times and places. But its original purpose has remained the same: To provide in one place the core of the instructions and rites for Anglican Christians to worship together. The Book of Common Prayer is the authority that governs our worship. The prayer book explains Christianity, describes the main beliefs of the Church, outlines the requirements for the sacraments, and in general serves as the main guidelines of the Episcopal life.