Why does a fire burn brighter when bellows are used to blue air onto it?

A fire burns brighter when bellows are used to blow air onto it because the increased airflow supplies more oxygen to the flames. Oxygen is a key component in the combustion process; more oxygen allows for more efficient and complete burning of the fuel. This leads to a higher temperature and a more intense flame, resulting in a brighter fire. Additionally, the turbulence created by the airflow helps to mix the gases better, enhancing the combustion reaction.