I often see questions on posts, and I have had quite a few personal messages, asking about The Book Of Shadows. Let me try to make it all make sense to the "newbies".
When I was young, and learning witchcraft, nobody had ever heard of a Book of Shadows! That title came much later as Gerald Gardner became better known to the public. Doreen Valiente said that it was always a good idea to keep a record of experience,thoughts,ideas,knowledge. But it does not have to be an actual book!
All the years when I was being taught witchcraft my teacher insisted that I write everything she told me in a notebook. I still have dozens of them!
So, a book of shadows is really a record of your life. Like a Diary. And just as you may have lots of diaries over many years, so you will also have many "books" of shadows.It may very well not be one book! But a number of books, papers, clippings, photographs; or just a pile of school exercise books like mine!