A fuel tank, also known as a gas tank, is a container that stores liquid or gas fuel for vehicles or machinery. The term "reservoir" may also be used to refer to a fuel tank. Other synonyms for a fuel tank include a petrol tank, oil tank, diesel tank, gasoline tank, or storage tank. Depending on the type of fuel being stored, alternative words for "fuel tank" may include propane tank, natural gas tank, kerosene tank, or ethanol tank. The size and shape of a fuel tank can also vary greatly, with terms such as barrel, drum, canister, or cistern being used to describe different forms of fuel storage containers.