This is a list of aircraft carriers of the Second World War. Aircraft carriers serve as a seagoing airbases, equipped with a flight deck and facilities for carrying, arming, deploying and recovering aircraft. Typically, they are the capital ships of a fleet, as they project air power worldwide without depending on local bases for operational support. Aircraft carriers are expensive and are considered critical assets. By the Second World War aircraft carriers had evolved from converted cruisers, to purpose built vessels of many classes and roles. Fleet carriers were the largest type, operating with the main fleet to provided offensive capability. Light aircraft carriers were fast enough to operate with the fleet but smaller and with fewer aircraft.