WorldCat

WorldCat is a very big online catalog, a list of books and things like books in tens of thousands of libraries in many countries.
WorldCat was built by OCLC, which is an organization of libraries. WorldCat is maintained by the group of libraries in OCLC. 
History.
In the 1970s, OCLC grew from a regional computer system for 54 Ohio colleges into an international network.
In 1979, the first Canadian and the first international library joined OCLC.
Timeline.
On August 26, 1971, the OCLC Online Union Catalog, now called WorldCat, went online.