A steamboat or steamship, sometimes called a steamer, is a ship in which the primary method of propulsion is steam power, typically driving propellers or paddlewheels. The term steamboat is usually used to refer to smaller steam-powered boats working on lakes and rivers, particularly riverboats; steamship generally refers to larger steam-powered ships, usually ocean-going, capable of carrying a (ship's) boat. The term steamwheeler is archaic and rarely used.