A catamaran (informally, a "cat") is a multi-hulled watercraft featuring two parallel hulls of equal size. It is a geometry-stabilized craft; that is, it derives its stability from its wide beam, rather than from a ballasted keel, like a monohull. Being ballast-free and therefore lighter than a monohull, catamarans often have a shallower draft (draught) than comparably-sized monohulls. The two hulls combined also often have a smaller hydrodynamic footprint than that of comparable monohulls, allowing for reduced drag and increased efficiency. The catamaran's wider stance on the water can reduce both heeling and wave-induced motion, as compared with a monohull.