What extinguishes a burning flame?

Water is an extinguisher of a burning flame.

Answer: FUEL: Like us, fires die without food. Firemen exploit this principle in forest and brush fires when they create a firebreak in the path of the main fire. In a kitchen setting, eliminating the fuel may simply mean turning off the gas. In other settings, however, eliminating the fuel may be difficult if not impossible.

OXYGEN: Once again, like us, a fire must breathe. Toss a shovelful of dirt or a fire blanket over a fire, and you smother it. The oxygen level, incidentally, need not go down to zero for a fire to suffocate. If you reduce the oxygen level from the normal 21 percent in the air around us to 15 percent, many substances-flammable liquids, for example, and even some solids-will no longer burn.