The acronym "ISBN" stands for "International Standard Book Number." Booksellers, libraries, universities, wholesalers and distributors use these unique 13-digit numbers to identify internationally published materials.
ISBNs are issued by agencies at the direct request of publishers, e-book publishers, audio cassette and video producers, software producers, and associations with publishing programs. The ISBN contains information about a publication, such as country or geographical region, publisher, title and edition as well as a check digit to validate the ISBN.
There are 160 agencies worldwide with permission to publish ISBNs. Each agency is assigned a country or geographical region, and only the assigned agency is authorized to issue an ISBN in that region.