A brig is a sailing vessel with two square-rigged masts. During the Age of Sail, brigs were seen as fast and maneuverable and were used as both naval warships and merchant vessels. They were especially popular in the 18th and early 19th centuries. Brigs fell out of use with the arrival of the steam ship because they required a relatively large crew for their small size and were difficult to sail into the wind. They are not to be confused with a brigantine which has different rigging. In the narrow technical field of sailing rigs, a brig is distinct from a three-masted ship by virtue of only having two masts.
Read more about Brig: Rigging, Hull Material, Development of The Brig, Historic Usage, Historic Examples, Brigs in Fiction, Modern Recreations