The Book of Shadows is the name used for a book that contains magical and religious texts in the religion of Wicca and other witchcraft traditions.
A Book of Shadows typically contains details of the witch’s personal spells, rituals, practices, ethics and philosophy of Wicca.
In British” Traditional Wicca”, which generally revolves around the structure of the coven, the book is traditionally copied by hand from that of one’s initiating High Priestess or Priest, who copied theirs in turn from their initiator.
But in” Eclectic Wiccan” (solitary practitioners) a Book of Shadows is usually a personal journal of the witch’s journey in witchcraft.
Witches usually make their own books but for “the curious ” like most things these days “The Book of Shadows” has been commercialised and can be found for sale in New Age shops and even on EBay.