Combustion is the chemical process of burning, where a substance combines rapidly with oxygen and releases energy as heat and light. When you strike a match, watch a candle flame, or see a campfire crackling, you're witnessing combustion in action.

For combustion to happen, you need three things: fuel (something that can burn, like wood or gasoline), oxygen (from the air around us), and heat (to start the reaction). Remove any one of these, and the fire goes out. That's why smothering a flame with a blanket works: you're cutting off its oxygen supply.

Combustion powers much of modern life. Car engines use the combustion of gasoline to create the power that turns the wheels. Power plants burn coal or natural gas through combustion to generate electricity. Even your body uses a slow form of combustion when it combines food with oxygen to create energy, though this happens at body temperature without flames.

Scientists distinguish between slow combustion, like rusting metal or digesting food, and rapid combustion, which produces the flames and heat we typically associate with fire. Understanding combustion helped humans harness fire's power for cooking, warmth, metalworking, and eventually the engines and power plants that transformed civilization.