Destroyer, a highly maneuverable warship of small to medium size. The destroyer is designed to attack enemy vessels, especially submarines, and to protect other types of ships from air, surface, and submarine attacks. To hunt out enemy submarines, destroyers are equipped with sonar. Many carry helicopters also equipped with detection devices. Antisubmarine weapons carried by destroyers include depth charges, torpedoes, and guided missiles.

Destroyers are also equipped with anti-aircraft guns and surface-to-air missiles. Some destroyers serve as floating radar stations. Many Russian destroyers, equipped with surface-to-surface missiles, are particularly suited to destroying other surface vessels.

The usual displacement for standard-size destroyers ranges from 3,000 tons to more than 4,000 tons. Guided missile destroyers, displacing from 4,500 to almost 8,000 tons, were developed in the 1960's. (In World War II, the U.S. Navy developed the destroyer escort, a vessel displacing about 3,000 tons. Destroyer escorts were originally designed to protect aircraft carriers from submarines. In the 1970's, destroyer escorts were reclassified as frigates.

The destroyer was developed around 1900 to combat the torpedo boat, a small, fast craft usually made of wood. The destroyer, originally called a torpedo-boat destroyer, was larger and carried more armament, yet was fast and maneuverable, and it soon replaced the torpedo boat. (The torpedo boats of World War II were an entirely different kind of vessel.) Large numbers of destroyers were built in both world wars, especially for defense against submarines.