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 therefore known as the Senior Service. From the end of the 17th century until well into the 20th century it was the most powerful navy in the world,  playing a key part in establishing the British Empire as the dominant world power.

The Royal Navy is a constituent component of the Naval Service, which also comprises the Royal Marines, Royal Naval Reserve and Royal Marines Reserve.

As of September 2011, there are 79 commissioned ships in the Royal Navy, plus 19 vessels of the Royal Fleet Auxiliary (RFA) which also contribute to the Royal Navy's available sea-going assets.