Gunpowder, in the form of black powder, is a dry explosive consisting generally of potassium nitrate or sodium nitrate, charcoal and sulfur, which, under normal conditions, deflagrates rather then detonates. It has a relatively low energy output as is classified as a low explosive. As it burns, a subsonic deflagration wave is produced rather than the supersonic detonation wave which high explosives produce. As a result, pressures generated inside a gun are sufficient to propel a bullet, but not sufficient to destroy the barrel. At the same time, this makes black powder less suitable for shattering rock or fortifications, applications where high explosives are preferred.

Modern Gunpowder contains no black powder at all and is called "Smokeless Powder". Smokeless powder is the name given to a number of gunpowder-like propellants used in firearms which produce negligible smoke when fired, unlike the older black powder which it replaced.

Smokeless powder consists of nitrocellulose (single-base powders), frequently combined with up to 50 percent nitroglycerin (double-base powders), and sometimes nitroglycerin and nitroguanidine (triple-base), corned into small spherical balls or extruded into cylinders or flakes using solvents such as ether.