An aircraft licence is necessary to be a pilot of most aircraft, both for commercial or private operation. There are a number of different types of aircraft licences, and these correspond to the different classes of aircraft, a pilot's level of experience, and whether the pilot is a civilian or military pilot. The different classifications of pilots and aircraft licences include: student, recreational, sport, private, commercial, and airline transport. The distinctions between them are based on the amount of flight experience a pilot has, and also on the privileges and restrictions put in place. For example, a private aircraft licence only allows a pilot to fly a plane for non-commercial uses, which means he cannot be compensated for flying passengers. When it comes to flight experience and qualifications, the requirements for a higher-class aircraft licence get more rigorous. In order to be a commercial pilot, a pilot must have already earned a private licence and accumulate a large number of flight hours, some of which are cross-country, night, solo, etc. The aircraft licence system is designed to keep pilots restricted to the class of aircraft they are licenced for or below.