A cruiser is a type of warship. The term has been in use for several hundred years, and has had different meanings throughout this period. During the Age of Sail, the term cruising referred to certain kinds of missions – independent scouting, commerce protection, or raiding – fulfilled by a frigate or sloop, which were the cruising warships of a fleet. Currently only three nations operate cruisers: the United States, Russia, and Peru. (BAP Almirante Grau is still in service with the Peruvian Navy, and is the last gun cruiser currently in service in any navy).