boat, generic term for small watercraft propelled by paddles, oars, sail, or motor, open or partially decked, and usually less than 45 feet (roughly 14 metres) in length. A vessel larger than this is customarily classed as a ship, although the word boat is often applied to certain working vessels—such as tugboats—that may be of considerable size.

The early forms of the boat were many, and their design and structure depended upon available material. Where suitable timber was at hand, the raft and later the dugout canoe developed. Where suitable timber was not available, reed and bamboo rafts, skin-covered canoes, and skin floats made by inflating the hides of small animals could be found. In some timbered areas bark canoes were used. It may be assumed that the boat developed from the canoe forms; it is evident that boats did not appear until long after various forms of canoes came into being.