An aircraft carrier is a warship designed with a primary mission of deploying and recovering aircraft, acting as a seagoing airbase. Aircraft carriers thus allow a naval force to project air power worldwide without having to depend on local bases for staging aircraft operations. They have evolved from wooden vessels used to deploy balloons into nuclear-powered warships that carry dozens of fixed wing and rotary-wing aircraft.

Aircraft carriers are typically treated as the capital ship of a fleet and are extremely expensive to build and important to protect: of the nine nations which possess an aircraft carrier, six of these nations possess only one such ship each. Twenty-one aircraft carriers are currently active throughout the world with the U.S. Navy operating 11 of them as of June 2011^[update].