The four methods of extinguishing fire are: smothering, cooling, diluting the oxygen and interrupting the chain reaction. Smothering a fire involves depriving it of its source of oxygen, such as by covering it with baking soda or sand. Cooling a fire is done by applying water or other liquids to reduce the temperature and decrease the rate of combustion. Diluting the oxygen around a fire involves spraying it with carbon dioxide or other inert gases, which can reduce the oxygen content in the air around the blaze. Finally, interrupting the chain reaction is done by using an extinguishing agent like Halon to disrupt the chemical reaction that fuels a fire.