Tracer ammunition allows marking targets during firefights but can be seen by both sides. This effect is much stronger at night. Tracers can be used as an additive to other ammunition types freely.
Tracer bullets contain a small pyrotechnic charge on the rear, which can be seen during night or day from far off. These help to aim the weapon in automatic fire and "paint" targets for allied units to attack. Tracers can be added to other types of bullets; for example, API-T bullets were common for aircraft machineguns during World War II.