Your users—and many others in your community who are not library members—are searching the complete WorldCat database with the WorldCat.org search box. However, after they have found an item of interest and localize their search to nearby WorldCat libraries that own the item, they only see the holdings of libraries that subscribe to FirstSearch/WorldCat Discovery. This subscription ensures that your library's holdings appear in WorldCat.org results, so they are visible to Web users arriving from search engines and WorldCat.org traffic partner sites such as Google, Wikipedia, and Goodreads. This gives your library visibility to people who do not regularly visit your website when seeking information.
A FirstSearch/WorldCat Discovery subscription also gives your staff use of the WorldCat Search API.