A ballistic vest is an item of protective clothing that absorbs impacts from gun-fired projectiles and shrapnel fragments from explosions. A soft vest, made from many layers of woven or laminated fibers, protects the wearer’s torso from projectiles fired from handguns, shotguns, and small fragments from explosives such as hand grenades. If metal or ceramic plates are used with a soft vest, it can protect the wearer from rifle shots as well. When combined with metallic components or tightly woven fiber layers, soft armor offers some protection to the wearer from stab and slash from a knife. Soft vests are commonly worn by police forces, private citizens, and private security guards, and hard-plate reinforced vests are mainly worn by combat soldiers in the armies of various nations as well as police armed response units.

Ballistic vests use layers of very strong fiber to catch and deform a bullet and spread its force over a larger portion of the vest fiber. A deformable handgun bullet mushrooms into a dished plate on impact with a well-designed textile vest. The vest absorbs the energy from the deforming bullet, bringing it to a stop before it can penetrate the overall matrix. Some layers may be penetrated but as the bullet deforms, the energy is absorbed by a larger and larger fiber area.

Bulletproof vests, unlike regular clothing, must undergo stringent protection testing as required by the National Institute of Justice (NIJ). Not all bulletproof vests are alike. Some protect against lead bullets at low velocity, and some protect against full metal jacketed bullets at high velocity. Vests are classified numerically from lowest to highest protection: I, II-A, II, III-A, III, IV, and special cases (those for which the customer specifies the protection needed). Each classification specifies which type of bullet at what velocity will not penetrate the vest. While it seems logical to choose the highest-rated vests (such as III or IV), such vests are heavy, and the needs of a person wearing one might deem a lighter vest more appropriate.