A boat is a vehicle used to travel on water. It is smaller than a ship and can be lifted out of the water and carried on a ship. Some boats have sails, some are powered by rowing with oars, and some use motors. Those that use steam engines are steamboats. There are some boats that can go underwater. They are called submarines. A narrowboat is a boat designed to be used on narrow canals. It is sometimes called a barge.
Historically, most boats have been constructed from wood. However, more recently built boats are often made of metals like steel and aluminium. Expensive boats may have parts made from fiberglass or composite materials and some even have helicopter pads.