"ISBN" stands for "International Standard Book Number".
The ISBN identifies a book or other book-like product (such as an audiobook) in a specific format and edition, but also the publisher. If an ISBN is obtained from a company other than the official ISBN Agency, or one of its channel partners, that ISBN might not identify the publisher of the title accurately. This can have implications for doing business in the publishing industry supply chain.
What is the purpose of an ISBN?
The purpose of the ISBN is to establish and identify one title or edition of a title from one specific publisher and is unique to that edition, allowing for more efficient marketing of products by booksellers, libraries, universities, wholesalers and distributor.
Are there other resources for ISBNs?
If you are located in the United States, or a territory of the USA (Puerto Rico, Guam, US Virgin Islands, etc.), Bowker is the official registration agency of the ISBN.