In a firefighting situation, a backfire is a fire intentionally lit in order to combust fuels in a controlled manner. This is usually done along a firebreak far ahead of a headfire the firefighters wish to stop. These fires are lit on the side of the firebreak the headfire is approaching, and winds created by the approaching fire draw the backfires towards it. In theory, when they meet the headfire will stop because all the fuels in front of it have been consumed by the backfire. (it's literally fighting fire with fire) This is often a successful method when conditions are right, so it is frequently used.