Armour also often refers in a modern military context to armoured fighting vehicle and the formations based around them.
All different parts of the human body have been fitted with specialized armour pieces, and an extensive nomenclature has grown up around this. The head and face is covered by a helmet (with the face protection sometimes being a visor[?]), hand and fingers by gauntlets, the chest by a breastplate[?], the lower legs by greaves[?] and so on. Often different armour pieces will cover overlapping parts of the body, as different materials and developments in armour made for shifting fashions.
Armour parts may be manufactured using a wide variety of materials and forms. During the Middle Ages, cloth, soft leather, boiled leather, chainmail and steel plates were often used. Today, ballistic cloth and ceramic plates are the most common choices, often combined with metal alloy plates.
In European history, common armour types were the lorica segmentata, the chainmail hauberk, the gambeson and later the full steel plate armour used by late medieval knights. In feudal Japan, laquered lamellar armours were popular.
Today, bullet proof vests made of ballistic cloth and metal plates are common among security staff and in brances of the military. For military infantry applications, lighter protection is often used to protect soldiers from grenade fragments and indirect effects of bombardment.
Military vehicles are commonly armoured to withstand the impact of shrapnel, bullets or shells, protecting the soldiers inside from enemy fire. The design and purpose of the vehicle determines the amount of armour plating carried, as the plating is often very heavy and excessive amounts of armour restrict mobility.
Composite (aka Chobham) armour was developed in the 1970s by the British and first used on the German Leopard II. It consists of layers of steel, ceramic, and plastic honeycomb, sometimes with layers of depleted uranium added. Composite is effective against both kinetic and shaped-charge munitions. Against kinetic penetrators, the brittle ceramic blunts the projectile while the softer steel layers absorb its kinetic energy. Still, it is significantly less effective against shaped charge munitions, so the depleted uranium layers are added to provide extra protection against kinetic penetrators. Also, spaced armour is is used to dissipate the energy of a shaped-charge warhead. It consists of simply leaving hollow spaces in the armour.
Reactive armour, initially developed by Israel, uses layers of high explosive sandwiched between steel plates. When a shaped-charge warhead hits, the explosive detonates and pushes the steel plates into the warhead, disrupting the charge's plasma flow. It is less effective against kinetic penetrators.
Sloping and curving armour both increase the effective thickness, as a projectile striking at an angle must cut through more armour than one impacting perpendicularly. They also increase the chances of deflecting projectiles. The sloping front armour of a tank is often called the glacis, and provides the best protection as it is assumed to be the easiest part of the tank to hit.
Recently, many manufacturers have added a spall liner to the inside of the armour, which is designed to absorb fragmentation (spallation) released from the impact of an enemy shell, protecting soldiers and equipment inside.