The key advantage of self-propelled over towed artillery is that it can be brought into action much faster.

Many are equipped with machine guns for defense against enemy infantry. However they are generally lightly armoured which is insufficient to withstand direct-fire combat, nonetheless this protects their crews against shrapnel and small arms and are therefore usually included as armoured fighting vehicles. Modern self-propelled artillery vehicles often mount their main gun in a turret on a tracked chassis so they superficially resemble tanks. In lieu of the standard tank's general-purpose main gun that fired both high explosive and anti-tank ammunition, direct-fire vehicles had specialized roles, with assault guns providing close fire-support for infantry and tank destroyers mounting an anti-tank gun to take on enemy armour. In the past, self-propelled artillery has included direct-fire vehicles, such as assault guns and tank destroyers, which were typically well-armoured vehicles often based upon the chassis of a tank. They are usually used for long-range indirect bombardment support on the battlefield. They are high mobility vehicles, usually based on continuous tracks carrying either a large field gun, howitzer, mortar, or some form of rocket/ missile launcher. Within the terminology are the self-propelled gun, self-propelled howitzer, self-propelled mortar, and rocket artillery. Self-propelled artillery (also called locomotive artillery) is artillery equipped with its own propulsion system to move toward its firing position.

British modern light tanks