Natural gas is a combustible, gaseous mixture of hydrocarbons, primarily methane, but also containing ethane, propane, butane, and pentane. It is found in underground reservoirs, and is often extracted from oil wells. Natural gas is odorless, colorless, and tasteless, and is composed of mostly methane, with small amounts of other hydrocarbons. It is a non-renewable energy source, and is used for heating, cooking, and electricity generation. Natural gas is also used as a fuel for vehicles, and is a major component of the global energy mix.