The Fleet Air Arm (FAA) is one of the five fighting arms of the Royal Navy and is responsible for the delivery of naval air power both from land and at sea. The Fleet Air Arm operates the F-35 Lightning II for maritime strike and the AW159 Wildcat and AW101 Merlin for commando and anti-submarine warfare. The Fleet Air Arm today is a predominantly rotary force, with helicopters undertaking roles once performed by biplanes such as the Fairey Swordfish. The Fleet Air Arm was formed in 1924 as an organisational unit of the Royal Air Force, which was then operating the aircraft embarked on RN ships—the Royal Naval Air Service having been merged with the Army's Royal Flying Corps in 1918 to form the Royal Air Force—and did not come under the direct control of the Admiralty until mid-1939. During the Second World War, the Fleet Air Arm operated aircraft on ships as well as land-based aircraft that defended the Royal Navy's shore establishments and facilities. From Wikipedia
