Marsh gas is a term used to describe the flammable gas composed mostly of methane that is produced in marshy areas, such as swamps and wetlands. There are several synonyms for the word marsh gas, including swamp gas, bog gas, and methane gas. These terms are used interchangeably to describe the same type of gas and are commonly associated with the natural biodegradation of organic matter in wetlands. While marsh gas can pose a potential fire hazard if it accumulates in a confined space, it also plays an important role in the Earth's carbon cycle and contributes to the greenhouse effect.