Including 3 billion items across 500 million records in 483 languages by 100 million authors, it is the most complete record of books known to exist. Before it was set up in 1998, people had to use the 754-volume National Union Catalog.
WorldCat works the exact same way as our catalog:
Search your keywords or subject and it'll generate a list of books.
It'll tell you if WM owns the book, and if not, who Does own it.
In most cases, WM can order it from the other library & you can pick it up right here in Swem - at no charge!