Bullet-proof vest

The term bullet-proof vest refers to body armor that covers the all or part of a wearer's torso.

Prior to the invention of modern fabrics, like kevlar, some fighters wore body armor designed to protect them from shrapnel.

Vests made from many layers of fabrics like kevlar can reduce the injury from being hit by a bullet. The kevlar can prevent a bullet from entering the wearer's body. But the bullet still surrenders its energy around the spot where it would have entered, if they weren't wearing body armor.

The more energy a bullet is carrying the more layers of kevlar are required.

Bullet proof vests, intended to protect the wearer from a high velocity rifle bullet, supplement the fabric layers with hard plates. These plates protect the wearer from the energy of the bullet, by spreading it over the entire plate. Plates are often some kind of ceramic, for reasons of weight, and, because energy from the bullet can be spent cracking the plate, not damaging the wearer.

The vests are typically designed to not impede the wearer's mobility, and this can leave large vulnerable holes for the wearer's arms and neck.