Explosive substances may be classified by their reaction, composition, or service use.

Military explosives are divided into two general classes, high explosives and low explosives, according to their rates of decomposition. They may be further classified according to use.

From the standpoint of their composition, explosives may be divided into explosive mixtures and explosive compounds.

Classification of explosives thus far has been based on characteristics. A more practical classification from the standpoint of the Aviation Ordnanceman is based on their service use:

PROPELLANTS AND IMPULSE EXPLOSIVES- These explosives are used to propel projectiles from guns, to propel rockets and missiles, launch torpedoes, and launch depth charges from projectors. They are all burning or low explosive.

DISRUPTING OR BURSTING EXPLOSIVES- Explosives of this classification are employed to create damage to the target under attack. They are high-explosive charges that are used alone or as part of the explosive charge in mines, bombs, depth charges, missile and torpedo warheads, and in projectiles as a burster charge.

INITIATING EXPLOSIVES- The initiation of an explosive reaction requires the application of energy in some form. Propellants are commonly ignited by the application of flame, while disrupting explosives are set off by a severe shock. The device used to initiate the burning of a propellant is called a primer. The device used to initiate the reaction of a disrupting explosive is called a detonator.

AUXILIARY EXPLOSIVES- These are large propellant charges and relatively insensitive disrupting explosives which require an intermediate charge, so that the flame or shock of the initiating explosive may be increased to ensure proper reaction of the main explosive charge. The intermediate or auxiliary explosive used with propellants is called an ignition charge and consists of a quantity of flame-producing material sufficient to engulf the propellant grains. The auxiliary explosive used with disrupting explosives is called a booster and consists of a quantity of high explosives more sensitive than the burster charge.

PYROTECHNIC SUBSTANCES- Military pyrotechnic substances are used to send signals by visual means, such as color, to illuminate areas of interest, to simulate other weapons or activities, and as ignition elements for certain types of weapons. Pyrotechnic compositions, with respect to rapidity of action, are low explosives because of their low rates of combustion.
The functional characteristics of pyrotechnic compositions are their luminous intensity (candlepower), burning rate, color, color value, and efficiency of light production. Thus, for military use, pyrotechnic compositions must have acceptable explosive as well as burning characteristics.

A military chemical agent is a substance that produces a toxic (casualty) or an irritating (harassing) effect, a screening smoke, and incendiary action, or a combination thereof. These agents include compounds and mixtures other than pyrotechnics and are used as fillers in artillery shell, mortar shell, grenades, rockets, and bombs. They are classified according to tactical use, physiological effect and purpose.

MILITARY GASES- A military gas is any agent or combination of agents that can produce either a toxic or irritating physiological effect. Such agents may be in solid, liquid, or gaseous state, either before or after dispersion. The military gas may be classed as persistent if it remains effective at its point of release for more than 10 minutes, or nonpersistent if it becomes ineffective within 10 minutes. Military gases can be further classified according to their toxic and irritating effects.

SCREENING SMOKE- A screening smoke is a cloud that consists of small particles of solids, liquids, or both, dispersed and suspended in air.

INCENDIARIES- An incendiary may be a solid, liquid, or a gelled semiplastic material that, by its intense heat and flame, can start fires and scorch combustible and noncombustible materials, as well as injure and inactivate personnel.

SIMULATED MILITARY GASES- Simulated agents are essentially mild nontoxic harassing agents (substitutes for the real agent) designed specifically for training purposes.