ISBN stands for "International Standard Book Number", a unique identifier for books, intended to be used commercially. It was created in the UK in 1966 by the booksellers and stationers W.H. Smith and originally called Standard Book Numbering or SBN. In 1970 it was adopted as international standard ISO 2108.

The International Standard Recording Code (ISRC) system is the international system for the identification of recorded music and music videos. Each ISRC is a unique identifier that can be permanently encoded into a recording or music video.

No. The International Standard Book Number is a 10- or 13-digit commercial identifier. The copyright date is a 4-digit year.

ISBN stands for International Standard Book Number. It is a unique identifier assigned to each edition and variation of a book. This number is used by publishers, booksellers, and libraries for cataloging and ordering purposes.

No, the name of the variable is its identifier.