A ship is a large vessel designed to float, fly, work or travel on water. Boats are often found in Inland Waterways (such as rivers and lakes) or in protected coastal areas. However, ships such as whale ships are designed to operate from ships in an offshore environment. In naval terms, a ship is a ship small enough to carry on another ship. Another less restrictive definition is a boat that can be lifted from the water. Some definitions don't differ in size because a bulk carrier 1000 feet (300 meters) long on a large lake is called an ore ship. For reasons of naval tradition, submarines are often referred to as "boats" rather than "boats", regardless of their size and shape. A ship is usually distinguished from a ship by its large size, shape, and cargo or passenger capacity.

Because of its intended use, available materials or local traditions, ships have many shapes, sizes and construction methods. Canoes have been used since prehistoric times, and various forms of boats have been used worldwide for transportation, fishing or sports. The patterns of fishing boats vary greatly, in part to suit local conditions. Cruise ships include ski boats, pontoons and sailboats. Boat house can be used for vacation or long-term living. Small ships can provide transportation to and from large ships or transport (reduce weight) goods. Lifeboats have rescue and safety functions. Ships can be powered by manpower (e.g. rowing), wind (e.g. sailing) and electric motors (e.g. motor boats driven by propellers driven by gasoline or diesel engines).