The book mark is a thin strip of paper, card, or fabric that is used to mark a reader's place in a book. It is usually inserted between the pages so that the reader can easily find where they left off. Book marks can be plain or decorative, and are often used as a way to personalize a book or as a gift for book lovers. Some book marks also have quotes, images, or designs related to the book or the reader's interests. Overall, the book mark is a simple yet essential tool for any avid reader.