A tracer round is a special form of ammunition that contains either a smoke-producing agent or an illuminating chemical. These additions allow the shooter to follow the path of the bullet in flight.
Tracer rounds can be used for a variety of purposes. The most common application is to adjust aim. Using tracer rounds, shooters can gradually hone in on the target by watching the round's placement. Tracers can also be used to mark the location of a target for other soldiers. Rounds that employ incendiary materials are relatively effective at starting fires. Tracer rounds are usually mixed with traditional ammunition at a ratio of one tracer for every four regular cartridges.