A book cover is packaging for a book, and it needs to do all the things successful packaging does. It needs to be attractive, particularly to the individual for whom the book is intended. It needs to convey information about the book, specific facts about the subject and the author, but also emotional information about the approach the book takes to the subject matter. The best covers come from a clear understanding of the unique qualities of the book and the audience for whom it is intended. After that, we hope, comes a little bit of inspiration.