U.S. Navy Aviation Ordnanceman AIRMAN Anthony Baka mans a .50 caliber machine gun as he stands a force protection watch as his ship, the Nimitz Class Aircraft Carrier USS DWIGHT D. EISENHOWER (CVN 69), transits through the Strait of Messina, Italy, on Oct. 22, 2006. EISENHOWER is currently deployed in support of maritime security operations in the region. (U.S. Navy photo by Mass Communication SPECIALIST 2nd Class Miguel Angel Contreras) (Released)

Aircraft carriers are warships that act as airbases for carrier-based aircraft. In the United States Navy, these consist of ships commissioned with hull classification symbols CV (aircraft carrier), CVA (attack aircraft carrier), CVB (large aircraft carrier), CVL (light aircraft carrier), CVN (aircraft carrier (nuclear propulsion) and CVAN (attack aircraft carrier (nuclear propulsion). The first aircraft carrier commissioned into the United States Navy was USS Langley (CV-1) on 20 March 1922.