Frigate (FF/FFG)

A frigate is a general-purpose escort warship smaller than a destroyer, built for anti-submarine and convoy protection with a secondary air-defense role. US hull classification uses FF for a gun/ASW frigate and FFG for a guided-missile frigate; the Oliver Hazard Perry class (FFG-7) was the long-serving US type, replaced by the Constellation class (FFG-62, ordered 2020). Modern frigates such as the Franco-Italian FREMM run 5,000 to 6,500 tons. The frigate sits between the corvette and the destroyer in size, cost, and weapon depth.