Marsh gas, also known as biogas, is a type of natural gas that forms in wetlands, swamps, and marshes. It primarily consists of methane, which is produced by the decomposition of organic matter in the absence of oxygen. This process is carried out by microorganisms, making marsh gas a renewable energy source. In addition to methane, marsh gas can contain small amounts of other gases, such as carbon dioxide and hydrogen sulfide. It is often released into the atmosphere, contributing to greenhouse gas emissions. However, marsh gas can also be captured and used for energy production, helping to reduce reliance on fossil fuels.