Natural gas is a fuel found deep underground that burns cleanly and produces heat. It forms over millions of years from ancient plants and tiny sea creatures that were buried under layers of rock and dirt. Heat and pressure slowly transformed this organic material into gas, which collects in pockets beneath the earth's surface.

People drill wells to bring natural gas up from underground, then send it through pipelines to homes, schools, and businesses. When you see a blue flame on a stovetop or a furnace heating a house in winter, that's often natural gas burning. Power plants also burn natural gas to generate electricity.

Natural gas is mostly made of a molecule called methane. It's called “natural” because it occurs in nature, unlike manufactured gases. In its pure form, natural gas has no smell, so companies add a distinctive odor (like rotten eggs) so people can detect dangerous leaks.

Before pipelines existed, natural gas was often just burned off at oil wells because there was no easy way to transport it. Today it's one of the world's most important energy sources, competing with coal, oil, nuclear power, and renewable sources like wind and solar power.