Incendiary rounds, ammo, are a type of ammunition for firearms which contains a compound that burns and can cause a fire.

It was first used in WWI and phosphorous was the ingredient that ignited the fire. These were deadly but the effective range was only 350 yards. During WWII, incendiary bullets found a new use: they became one of the preferred types of ammunition for use in interceptor fighters. They were not good at hitting bomber aircraft or piercing armor but were far more effective than standard bullets because they could ignite fuel if they came into contact with a fuel tank or pipeline.

In modern times, Incendiary projectiles, in particular those intended for armor penetration, are more effective if they explode after penetrating a surface layer, such that they explode inside the target.

Targets with onboard electronics or computers can be damaged by metal fragments when they explode on the surface. Ignition is often delayed by varying means until after impact. Some explosive projectiles, such as high-explosive incendiary bullets, contain an incendiary charge intended to ignite explosives within the shell.

There are bullets, artillery (and mortar) shells, aerial bombs, and hand grenades designed to ignite inflammable objects and destroy manpower and combat equipment. Incendiary artillery (mortar) shells and aerial bombs are filled with such materials as incendiary thermite compositions and phosphorus. In Vietnam, American forces used incendiary aerial bombs and high-explosive shells filled with napalm. Incendiary ammunition that combines incendiary action with other types of destruction is also used, including fragmentation-incendiary shells and armor-piercing incendiary shells and bullets.

Incendiary rounds, have been around for decades and are becoming more sophisticated and used for sport shooting as opposed to strictly military use.