A bullet proof vest, more accurately called a bullet resistant vest, is a protective garment that is designed to protect the wearer from the impact of bullets and shrapnel. Unlike body armor, which is made from hard plates, vests are made from soft materials and are designed to be lightweight, flexible, and comfortable. Many people in the field of law enforcement wear bullet proof vests on the job to protect themselves.
The earliest form of body armor designed to resist bullets was developed in the 1500s, when soldiers realized that their traditional plate armor was not up to the recently introduced concept of the gun. As early as 1919, several people applied for patents for designs that resisted bullets, but the real breakthrough in this technology came in the late 20th century, with the development of extremely strong and durable fibers like Kevlar®. Kevlar® and similar artificial fibers allowed companies to manufacture soft, flexible, and extremely strong vests that offered protection from bullets.
The science behind the bullet proof vest is pretty simple. When a bullet hits the vest, it encounters multiple layers of very strong, criss-crossed fibers. These fibers slow the progress of the bullet and distribute its force, causing the bullet to flatten out and stop in the layers of the vest before it can reach the body of the wearer. Typically, the wearer experiences some blunt force trauma caused by the impact, but this is much better than a bullet wound.
In order to function, the vest needs to be thick and bulky, to provide enough layers of fibers to stop the bullet. This can make it uncomfortable to wear, although modern designs are an improvement over earlier versions. Modern vests can usually be worn concealed under garments, and they come in a variety of cuts and designs that provide coverage while also sitting comfortably on the body.
In addition to resisting bullets, many bullet proof vests can also cope with attempted stabbings. The layers of material distribute the force of the knife while slowing its progress, making it difficult for an assailant to cut the areas of the body protected by the vest.
These devices only protect the torso, which means that the head and extremities are still vulnerable to injuries. This is an important safety consideration for people who wear such vests, as they are far from invulnerable. They simply make some jobs a little bit safer.