ISBN stands for International Standard Book Number. It is a system that dates back to 1970 and is used for registering books and giving each a unique identifying number; ISBNs are used internationally. Generally, publishers are the ones who apply for an ISBN, and the first set of numbers that are unique to that publisher is referred to as the publisher's prefix.
Early in the 19th century both the United States and United Kingdom were working on developing an international directory of every book published. The goal was to keep the publishing industry strong and healthy. The directories they created were the beginning of the current ISBN bibliography used today. The ISBN system covers books currently in print, those out of print, and those about to be published.
Even though the early promoters of a centralized book directory did not realize it, they paved the way for the future computerization of all publications. By having a standardized numbering system, the ISBN organization is able to keep track of all books in print. This is an amazing task when you consider that there are approximately 50,000 new titles published each year.
The current ISBN recording system allows for publications to be read by machine, a process that has revolutionized the international book trade. There are currently 159 countries and territories that are official members of the ISBN organization. The organization acts as a trade association providing other services beyond book registration to publishers throughout the world. These services include assigning a Bowker Bar Code to each ISBN so that it can be scanned at retailers. The group also provides a list of recommended book printers and related resources for publishers.