The date of publication of a book. Book drifting records book drifting activities, so that children can choose their favorite picture books in class and take them home to read with their parents. Book drifting time is the date when books drift out. 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.