Methane is the main hydrocarbon component of natural gas and has the formula CH₄.
A methane molecule contains one carbon atom bonded to four hydrogen atoms. Its atoms form a tetrahedral arrangement around carbon, making methane the simplest alkane. Under ordinary conditions, it is a colorless, odorless gas; the familiar smell of domestic natural gas comes from added odorants, not methane itself.
Methane forms when organic matter decomposes without much oxygen, including in wetlands, landfills, and some geological settings. It is also produced in the digestive systems of ruminant animals and during fossil-fuel extraction and transport.
Methane burns to form carbon dioxide and water. It is a potent greenhouse gas, so leaks from energy systems and other sources are an important environmental concern. Methane should not be confused with ethane, C₂H₆, the second-smallest alkane.