What is the most common method of extinguishing a fire?

The most common method of extinguishing a fire is to cool the burning material. This approach leverages the principle that reducing the temperature of the material below its ignition point disrupts the fire's combustion process. Water is often used as a cooling agent in firefighting because it has a high heat capacity, which means it can absorb a significant amount of heat without rapidly increasing in temperature itself. By cooling the materials involved in the fire—such as combustible solids or liquids—you effectively lower their temperature and slow down or stop the chemical reactions that sustain combustion.

This method is particularly effective for Class A fires, which involve ordinary combustibles like wood, paper, and textiles, as these materials can be easily cooled to extinguish the flames. While other methods such as excluding oxygen, removing fuel, and inhibiting chemical reactions are also valid fire suppression techniques that can be effective in certain situations, cooling the burning material remains the most straightforward and widely used primary approach in many firefighting scenarios.