Where did gas originally come from?

Gas, particularly natural gas, primarily originates from the decomposition of organic matter, such as ancient plants and marine organisms, over millions of years under heat and pressure within the Earth’s crust. This process occurs in sedimentary rock formations, where the organic material is transformed into hydrocarbons. Natural gas often accompanies oil deposits, but it can also be found in standalone gas fields. Additionally, some gases are produced through geological processes unrelated to organic matter, such as volcanic activity.