The Book of Shadows – in traditional Wicca, this is a collection of ritual texts and descriptions of rituals handed down to an initiate by their High Priest or High Priestess. The Book of Shadows is passed on after the act of initiation. In some lineages the rule is that new material may only be added and nothing may be removed; in others this rule does not apply.
A magical diary, in which a witch records their own experiences, reflections, the spells they use or entire rituals, is often mistakenly taken for a Book of Shadows.
There is a fairly widespread belief that a Book of Shadows should be copied out or written by hand. There is no single view on what it should look like or what materials it should be made of; that depends on the inventiveness of its owner.
In eclectic Wicca (or rather in the various strands of modern paganism inspired by Wicca), these rules are not followed. A Book of Shadows can be drawn from any source, or you can even write one yourself. There are at least several published versions of the Book of Shadows written for people practising eclectic Wicca. In Poland one of the better known is Scott Cunningham’s Book of Shadows of the Standing Stones, published in his book “Wicca: A Guide for the Solitary Practitioner”. Another Book of Shadows in use is Doreen Valiente’s “Liber Umbrarum”, published in her book “Witchcraft for Tomorrow”. There are also online versions of Books of Shadows that eclectic Wiccans can use.