* Natural gas: Methane makes up about 80-95% of natural gas, which is used as a fuel for electricity generation, heating, and cooking.

* The atmosphere: Methane is a greenhouse gas, meaning it traps heat in the atmosphere and contributes to global warming. While its concentration is lower than carbon dioxide, it is a far more potent greenhouse gas.

* Biogas: Biogas is a mixture of methane and carbon dioxide produced by the anaerobic digestion of organic matter, such as sewage sludge and animal waste. It can be used as a renewable energy source.

* Landfills: Methane is produced by the decomposition of organic waste in landfills.

* Coal mines: Methane is released from coal mines as a byproduct of coal mining.

* The digestive system of animals: Methane is a product of the digestive process of ruminants, such as cows and sheep.

* Outer space: Methane has been found in the atmospheres of other planets and moons, including Saturn's moon Titan.

It's important to note that while methane is a valuable energy source, its release into the atmosphere contributes to climate change. Reducing methane emissions is a critical step in mitigating the effects of climate change.