The Naval Service is the maritime branch of the British Armed Forces. It comprises: From the latin maritimus, maritime refers to things relating to the sea. ... The armed forces of the United Kingdom are known as the British Armed Forces or Her Majestys Armed Forces, officially the Armed Forces of the Crown. ...

• the Royal Navy, which since 2000 has included Queen Alexandra's Royal Naval Nursing Service;
• the Royal Marines;
• the Royal Fleet Reserve, the regular reserve of the Royal Navy and the Royal Marines;
• the Royal Naval Reserve (including Queen Alexandra's Royal Naval Nursing Service (Reserves)), the volunteer reserve of the Royal Navy;
• the Royal Marines Reserve, the volunteer reserve of the Royal Marines.

The term is an official one, and is not in widespread use: most people, in the UK and elsewhere, refer to the service as a whole as the Royal Navy (e.g., by describing the Royal Marines as part of the Royal Navy). The Royal Navy of the United Kingdom is the senior service of the British armed services, being the oldest of its three branches. ... The Corps of Royal Marines, usually just known as the Royal Marines (RM), are the United Kingdoms amphibious forces and a core component of the countrys Rapid Reaction Force. ... The Royal Naval Reserve (RNR) is the volunteer reserve force of the Royal Navy in the United Kingdom. ...