HMS Ark Royal (R09) was an Audacious-class

Audacious class aircraft carrier

The Audacious class aircraft carriers were a class of ship proposed by the British government in the 1930s - 1940s.- History :The Audacious class was originally designed as an expansion of the Implacable class with double storied hangars...

 aircraft carrier

Aircraft carrier

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...

 of the Royal Navy

Royal Navy

The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 and, when she was decommissioned in 1978, was the Royal Navy's last remaining conventional catapult and arrested-landing

CATOBAR

CATOBAR is a system used for the launch and recovery of aircraft from the deck of an aircraft carrier...

 aircraft carrier. She was the world's first aircraft carrier to be commissioned with an angled flight deck

Flight deck

The flight deck of an aircraft carrier is the surface from which its aircraft take off and land, essentially a miniature airfield at sea. On smaller naval ships which do not have aviation as a primary mission, the landing area for helicopters and other VTOL aircraft is also referred to as the...

, preceding the first American carrier commissioned with this feature, USS Forrestal, by eight months.
Ark Royal was the sister ship to HMS Eagle

HMS Eagle (R05)

HMS Eagle was an aircraft carrier of the Royal Navy, in service 1951-1972. With her sister ship , she is one of the two largest British aircraft carriers yet built....

, which was initially named HMS Audacious

HMS Audacious

Several ships of the British Royal Navy have been named HMS Audacious. was a 74-gun 3rd rate in service from 1785 to 1815. was a battleship launched in 1869, converted to a depot ship in 1902, later named Fisgard then Imperieuse, and sold for breakup in 1927.* HMS Audacious was launched in 1897 as...

, hence the name of the class.