An aggregator is a company used by local search directories to maintain and supply their business database. The most important U.S. aggregators are Acxiom, Factual, Infogroup, and Localeze. These companies gather data about businesses from both offline and online sources including phone bills, business registration records, chamber of commerce membership rosters, and many other sources. An aggregator is also known as a “data aggregator” or “data provider.”