The propellant material used in most gun systems. Divided into two basic types: smokeless powder and black powder.

It is produced in a wide variety of types, forms and brand names intended for specific applications. It varies chiefly according to burning speed.

The fast-burning types are used for light bullets in short barrels at low velocities: slower-burning powders are used in longer barrels and in greater quantities to drive the bullet at higher velocities. Most powder contains a major percentage of nitrocellulose, with small traces of other compounds intended to control burning rate or prevent deterioration; such powder is called single-base; smokeless powders containing a percentage of nitroglycerine are called double-base. Powders containing substantial amounts of other organic nitrates are called multi-base. Further identified by shape of individual kernels or granules.