An ISBN number, or International Standard Book Number, is a unique identifier for books. It helps publishers, booksellers, and libraries easily find and manage specific titles. Each ISBN is a 10 or 13-digit number that provides information about the book's edition, publisher, and format. ISBNs are essential for the book industry, as they streamline the process of ordering and selling books. When a book is published, it is assigned an ISBN, which remains with it throughout its life. This system ensures that each book can be accurately tracked and distinguished from others in the vast world of literature.