Autocannon in the context of "Fragmentation (weaponry)"

Anti-aircraft warfare (AAW) or air defence (or air defense in American English) is the counter to aerial warfare and includes "all measures designed to nullify or reduce the effectiveness of hostile air action". It encompasses surface-based, subsurface (submarine-launched), and air-based weapon systems, in addition to associated sensor systems, command and control arrangements, and passive measures (e.g. barrage balloons). It may be used to protect naval, ground, and air forces in any location. However, for most countries, the main effort has tended to be homeland defence. Missile defence is an extension of air defence, as are initiatives to adapt air defence to the task of intercepting any projectile in flight.

Most modern anti-aircraft (AA) weapons systems are optimised for short-, medium-, or long-range air defence, although some systems may incorporate multiple weapons (such as both autocannons and surface-to-air missiles). 'Layered air defence' usually refers to multiple 'tiers' of air defence systems which, when combined, an airborne threat must penetrate to reach its target; this defence is usually accomplished via the combined use of systems optimised for either short-, medium-, or long-range air defence.

An infantry fighting vehicle (IFV), also known as a mechanized infantry combat vehicle (MICV), is a type of armoured fighting vehicle, light tank, and armoured personnel carrier used to carry infantry into battle and provide direct-fire support. The 1990 Treaty on Conventional Armed Forces in Europe defines an infantry fighting vehicle as "an armoured combat vehicle which is designed and equipped primarily to transport a combat infantry squad, and which is armed with an integral or organic cannon of at least 20 millimeters calibre and sometimes an antitank missile launcher". IFVs often serve both as the principal weapons system and as the mode of transport for a mechanized infantry unit.

Infantry fighting vehicles are distinct from general armored personnel carriers (APCs), which are transport vehicles armed only for self-defense and not specifically engineered to fight on their own. IFVs are designed to be more mobile than tanks and are equipped with a rapid-firing autocannon or a large conventional gun; they may include side ports for infantrymen to fire their personal weapons while on board.

Close air support (CAS) is defined as aerial warfare actions—often air-to-ground actions such as strafes or airstrikes—by military aircraft against hostile targets in close proximity to friendly forces. A form of fire support, CAS requires detailed integration of each air mission with fire and movement of all forces involved. CAS may be conducted using aerial bombs, glide bombs, missiles, rockets, autocannons, machine guns, and even directed-energy weapons such as lasers.

The requirement for detailed integration because of proximity, fires or movement is the determining factor. CAS may need to be conducted during shaping operations with special forces if the mission requires detailed integration with the fire and movement of those forces. A closely related subset of air interdiction, battlefield air interdiction, denotes interdiction against units with near-term effects on friendly units, but which does not require integration with friendly troop movements. CAS requires excellent coordination with ground forces, typically handled by specialists such as artillery observers, joint terminal attack controllers, and forward air controllers.

Saturation fire is a saturation attack using an intense level of artillery bombardment or rapid direct fire (from automatic weapons such as machine guns, autocannons or rotary guns) that is designed to overwhelm a target area with lethal firepower, for the purpose of suppression, area denial or mass destruction of the enemy.

Rifling is the term for helical grooves machined into the internal surface of a firearms's barrel for imparting a spin to a projectile to improve its aerodynamic stability and accuracy. It is also the term (as a verb) for creating such grooves. The opposite of rifling is smoothbore.

Rifling is measured in twist rate, the distance the rifling takes to complete one full revolution, expressed as a ratio with 1 as its base (e.g., 1:10 inches (25.4 cm)). A shorter distance/lower ratio indicates a faster twist, generating a higher spin rate (and greater projectile stability).

A machine gun (MG) is a fully automatic and rifled firearm designed for sustained direct fire. Automatic firearms of 20 mm (0.79 in) caliber or more are classified as autocannons rather than machine guns.

As a class of military kinetic projectile weapons, machine guns are designed to be mainly used as infantry support weapons and generally used when attached to a bipod or tripod, a fixed mount or a heavy weapons platform for stability against recoil. Many machine guns also use belt feeding and open bolt operation, features not normally found on other infantry firearms.

A weapons platform is generally any structure, vehicle or mechanism on which a weapon can be installed (via various mounting mechanisms) for optimal stability and performance. The mounted weapons, the platform and all other associated supporting equipments together form the weapon system.

In more general use, a weapons platform could be structured around a gun, such as a gun turret on a ship, or bracing on an aircraft. For example, a jet aircraft is a weapons platform for missiles, bombs or autocannons, and the resultant weapon system is the fighter jet; a motorboat can serve as a weapons platform for automatic weapons, torpedoes and flamethrowers, resulting in weapon systems such as gunboats and fast attack crafts. Land vehicles, either wheeled, tracked or mixed, are also considered weapons platforms for grenade launchers, machine guns, recoilless guns and some missile launchers, which transform the vehicles into weapon systems such as armored cars (such as the Humvee), IFVs and technicals (improvised from civilian pickup trucks). In addition, artificial satellites have been proposed as potential space weapon platforms. These satellites could carry an arsenal of weapons, such as to threaten other countries with the possibility of an orbital nuclear strike (see Rods from God).

Air-to-ground weaponry is aircraft ordnance used by combat aircraft to attack ground targets. The weapons include bombs, machine guns, autocannons, air-to-surface missiles, rockets, air-launched cruise missiles and grenade launchers.