BUREAU INTERNATIONAL DES EXPOSITIONS (BIE)
The Bureau International des Expositions (BIE) was founded in 1928 and began operations in 1931. It supervises the correct application of the Convention Relating to International Exhibitions on behalf of 170 member countries. The BIE has its headquarters in Paris, France.
Not all events that most people would categorize as a world fair have been sanctioned by the BIE, notably the 1964-1965 New York World's Fair.
Currently, the BIE regulates Registered expositions that are held in years ending in 0 and 5, and Recognized expositions that are allowed to happen once in between each larger expo (but not in an adjacent year).