The Book of Shadows is a typical part of Wiccan practice. It is usually begun at the start of one's studies, and is used to keep a record of the things the person has learned, or other things such as: the Rede, herbs and their magickal properties, crystals, different forms of magic, runes and various other knowledge. It is often advised to keep the Book of Shadows private, and that the owner should be the only one to use it directly; other's energies may interfere. As there is no holy book for Wiccans, the Book of Shadows is thought to be one's own personal interpretation of the Wiccan religion. It is used to store useful articles to further one's knowledge. The Wiccan Rede is usually printed on one of the first pages. The Book of Shadows is sometimes linked to or named the Book of Mirrors or the Book of Light, although they can be different things. They are used by Wiccans who practice alone (Eclectic) and others.
An initiate is oathbound to keep the contents of the Book of Shadows secret. It may only be shown to other initiates, generally to allow new initiates to copy its contents.
It is written in ones own handwriting, as in times when other means of copying where as yet un-invented, or prohibitively expensive for many, the only alternative would be to have possession of a book in the handwriting of another initiate, which would risk their exposure should the book be captured. Some traditions suggest that the contents of the Book of Shadows be written in code; i.e. one of the magical alphabets, depending upon tradition.
While the "core" material copied would be identical with that which it is copied from, some traditions allow people to add personal additions, but these are sometimes considered separate to the Book of Shadows proper.
Thoughts and beliefs around the Book of Shadows may differ per Wiccan due to different branches of the religion.
Various people have tried creating dynamic Books of Shadows here on Wikia, with limited success and using up various names. The most recent effort is at the Black Book Wiki.