Ships come in many types and are used for various purposes. They are generally distinguished from boats based on their large size, distinct shape, and ability to carry cargo or passengers. Some main types of ships include bulk carriers which transport unpackaged bulk goods, container carriers which use intermodal containers, general cargo ships which move packaged goods, vehicle carriers which carry cars and trucks, and passenger ships whose primary function is to carry people. Other ship types specialize in transporting liquids like oil, gas, or chemicals in tankers or transporting perishable goods, fish, animals, or refrigerated items.