Combustion devices are tools or machines that burn fuel to produce energy, typically in the form of heat or power. Common examples include internal combustion engines found in cars and furnaces used for heating buildings. These devices rely on a chemical reaction between fuel and oxygen, resulting in combustion. The process of combustion can be classified into two types: complete and incomplete. In complete combustion, fuel burns efficiently, producing carbon dioxide and water. Incomplete combustion occurs when there is insufficient oxygen, leading to the production of harmful byproducts like carbon monoxide and soot. Proper maintenance of combustion devices is essential for safety and efficiency.