A light cruiser is a type of small or medium-sized warship. The term is a shortening of the phrase "light armored cruiser", describing a small ship that carried armor in the same way as an armored cruiser: a protective belt and deck. Prior to this smaller cruisers had been of the protected cruiser model, possessing armored decks only. While lighter and smaller than other contemporary ships they were still true cruisers, retaining the extended radius of action and self-sufficiency to act independently around the world. Cruisers mounting larger guns and heavier armor relative to most light cruisers would come to be known as heavy cruisers, though the designation of 'light' versus 'heavy' cruisers would vary somewhat between navies. Through their history light cruisers served in a variety of roles, primarily as convoy escorts and destroyer command ships, but also as scouts and fleet support vessels for battle fleets.

The armored cruiser was a type of warship of the late 19th and early 20th centuries. It was designed like other types of cruisers to operate as a long-range, independent warship, capable of defeating any ship apart from a battleship and fast enough to outrun any battleship it encountered.