In passing conversation the other day, I was asked what the difference between a Grimoire and a Book of Shadows (BOS) is. Most witches keep a BOS, but not a Grimoire. A BOS is a witch's personal book of magic; a diary of magic if you will. It includes records of all magical workings, dreams and their meanings, rituals, etc. If the witch does not also keep a Grimoire, it can also include spells and other magical information needed to perform magic. Its always a good idea to keep records of your magical workings. This will not only help you progress as a witch by seeing your power grow, but will also allow you to see what works and what does not work for you.
A Grimoire is like a BOS, but not as personal. It holds information about rituals, spells, potions, and how to prepare magical tools. It also contains lists of correspondences and magical properties of herbs, gemstones, food, colors, etc. Basically, it contains all your magical research. It does not contain personal information or records of magical workings.
Most witches keep just a BOS. I am personally in the process of transferring to two separate books. I'd much rather keep all my research in one book and my thoughts and feelings in another book. In doing so I can keep my personal information from others while still sharing my research.
If you wish to start a Grimoire, I suggest using something with removable pages. This way you can add and remove pages as you need them instead of taking your entire book into a ritual where it may be damaged. This also allows you to easily move pages around if you decide to reorganize it. Some people keep their BOS and Grimoires on their computer. I find this cumbersome when I wish to perform magic, but it may work for you.
Remember, your BOS contains very personal information. It is a sacred object and should be treated as such. Honor it by giving it its own special hiding place where others will not be tempted to mess with it. Bless it and protect it. It is only for you and whoever you authorize to see it. You need to be sure that whoever does see it won't disclose its contents to others or harm you or the book. If someone makes you uncomfortable, do not show it to them. This is just another reason I suggest keeping two books. Others like to see your research, not so much your personal thoughts. Keeping a Grimoire and a Book of Shadows is the best way to do this.
I hope this clears up any confusion you may have. Do you keep just a BOS or a BOS and Grimoire?