A corvette (sometimes corvet) is a small, maneuverable, lightly armed warship, originally smaller than a frigate (2000+ tons) and larger than a coastal patrol craft or fast attack craft (500 or fewer tons), although many recent designs resemble frigates in size and role. During the Age of Sail, corvettes were smaller than frigates and larger than sloops-of-war, usually with a single gun deck.
Although almost all modern navies use ships smaller than frigates for coastal duty, not all of them use the term corvette (via Middle French, from a Dutch word corf, a type of boat) or equivalent. The rank "corvette captain", equivalent in many navies to "lieutenant commander", derives from the name of this type of ship.
Read more about Corvette: Sailing Vessels, Steam Ships, World War II, Modern Corvettes, Corvettes Preserved As Museum Ships