An airline is an organization that provides air transport services for traveling passengers and freight. Airlines lease or own their aircraft with which to supply these services and may form partnerships or alliances with other airlines for mutual benefit. Generally, airline companies are recognized with an air operating certificate or license issued by a governmental aviation regulatory body. Airlines vary from those with a single aircraft carrying mail or cargo, through full-service international airlines operating hundreds of aircraft. Airline services can be categorized by variety of parameters such as area of operations, type of license, size of fleet and types of aircrafts operated, type such as passenger or cargo and finally on their business models such as full service or low cost model.