Harrier were the first successful fighter aircraft capable of vertical takeoff and landing, although short takeoff and vertical landing is preferred. Variants are used by the Royal Air Force, Royal Navy, and United States Marine Corps.
As of 2000, the British military no longer differentiate between sea and land Harriers. The 1998 Strategic Defence Review which announced the creation of a "Joint Force 2000" (JF2000, with the mission "To provide a force able to deploy from land and sea, capable of precision attack of sea, land and air targets, able to undertake timely reconnaissance, and air escort of joint and allied assets." 
Developed by Hawker Siddeley, the original operational version, principally intended for NATO roles where it could be dispersed into forests and other concealment, and then rise to carry out close air support and battlefield air interdiction.
Sea Harriers had a decisive air superiority role in the Falklands War; a large part of their effectiveness was due to their AIM-9L Sidewinder missiles, which could engage an enemy aircraft from all directions. In addition, they were operating near their carrier, while the Argentinian aircraft were near the limit of fuel endurance. They were generally more maneuverable than their enemies.
A 2010 British defence review is retiring the Sea Harrier and the aircraft carrier HMS Ark Royal (1985), to make funds available for the new aircraft carriers that will not be available until 2019.