A book is a medium for recording information in the form of words or images, and usually consists of many pages (made of papyrus, parchment, kraft paper or paper) bound together and protected by a cover. The technical term for this physical arrangement is codices. In the history of hand-held physical support used to expand written works or records, manuscripts replaced their predecessor volumes.

The knowledge in a physical book is not necessarily a composition, or even a book. Books can only contain pictures, printed matter or photos, crossword puzzles or paper-cut dolls. In a physical book, a page can be blank, or it can contain a set of abstract lines to support entries, such as in an account book, appointment book, signature book, notebook, diary or sketch book. The pages of some physical books are thick and strong enough to support other physical objects, such as scrapbooks or photo albums. Books can be distributed in electronic form, such as e-books and other formats.