The International Standard Book Number (ISBN) is a unique identifier for books, allowing publishers, libraries, and retailers to easily track and manage them. Each ISBN consists of 13 digits, which help distinguish one book from another, even if they share the same title. This system simplifies the process of ordering and selling books, ensuring that readers can find the exact edition they want. Introduced in 1970, the ISBN has become essential in the publishing industry. It is often found on the back cover of a book, alongside the barcode. By using the ISBN, authors, publishers, and booksellers can efficiently manage their inventory and sales, making it easier for readers to discover new titles.