ISBN: The Standard Book Number

The internationally agreed number given to a book is called the ISBN, which stands for International Standard Book Number.

An ISBN is a unique numeric commercial book identifier. It is used internationally to identify books uniquely. Each edition and format of a book (e.g., hardcover, paperback, e-book) is assigned its own unique ISBN.

Understanding Other Standard Numbers

While ISBN is specifically for books, other standard numbers exist for different types of publications:

• ISSN: This stands for International Standard Serial Number. It is used to identify serial publications such as magazines, journals, and newspapers. It is not used for books.
• ISMN: This stands for International Standard Music Number. It is used to identify individual print music scores. It is not used for general books.
• ISSDN: This is not a standard or widely recognized identifier for publications in the way ISBN, ISSN, or ISMN are.

Therefore, the correct identifier for a book among the given options is the ISBN.