Natural gas is a mix of gases, primarily short hydrocarbons like methane and propane as well as other combustible gases like hydrogen sulphide. Natural gas reserves are usually part of other fossil fuel deposits as they are emitted as the fossil fuel forms.
Natural gas is primarily used in the Northern hemisphere, with North America and Europe being the main consumers with approximately 1,500 billion cubic metres being consumed in 2015. It is commonly used domestically for a variety of tasks such as heating and cooking as well as commercially in power generation.
Natural gas can be obtained from a variety of sources. Originally it was obtained as a by product of oil extraction or in coal fields, but non associated sources also exist. It can also occur naturally in shale rock, naturally it does not flow however through a process called hydraulic fracturing (fracking) it can be extracted. Finally it can be obtained as a production of bio-degradation under anaerobic conditions, such as in landfills, which can be harvested for use - although this is considered a renewable resource.