Combustion reactions are chemical processes where a substance, typically a hydrocarbon, reacts with oxygen to produce energy, carbon dioxide, and water. These reactions are exothermic, meaning they release heat. Common examples include burning fuels like gasoline or natural gas, which are essential for powering vehicles and heating homes. There are two main types of combustion: complete and incomplete. In complete combustion, sufficient oxygen is present, resulting in carbon dioxide and water as products. Incomplete combustion occurs when there is not enough oxygen, leading to the production of carbon monoxide and soot, which can be harmful to health and the environment.