The Book of Shadows belongs to the Halliwell family. It was written by the ancestors of the Charmed Ones. Different spells were added to the book by witches in the family. Phoebe was the first to find the book in the attic out of the three sisters (Prue, Piper, and Phoebe). Phoebe read an incarnation in the Book of Shadows which let along to them getting their powers.