For almost 40 years bulletproof vests or body armor has been used to protect military officers and law enforcement staff against penetration from ballistic threats. Over those years several different materials have been used as body armor in an attempt to protect vital organs from injury from direct bullet impact or fragmentation caused by shards and pieces of exploding projectile matter.

The technology behind body armor and bulletproof vests has progressed significantly from humble beginnings when protective armor was created from leather, wooden shields or cumbersome plate mail. Of course in the times when these forms of body armor were used, they were well-suited to the type of attack expected. They were created to fend off attack from blades or edged weaponry.
 
As the technological advancements behind weapon creation have advanced, so too has the technology behind creating adequate protection against them have advanced. While modern ballistic weaponry improves and becomes far more advanced, the body armor used to protect against attack from the massive kinetic energy generated by these weapons also needs to be far superior to match.
 
First Body Armor in the USA
 
As early as the first part of the 1900s, patent records show early versions of body armor created and designed by engineers. By the 1930s, a form of bullet proof vest had been designed and documented, however it's worth noting that these early attempts were unwieldy, cumbersome and too expensive to produce to be considered effective. They were also not completely effective for protecting against attack from higher velocity bullets.
 
As technology advanced, so too did the level of design and efficiency when creating bullet proof vests. Experimentation with soft body armor brought with it the advent of silk threat woven through the armors fabric to reinforce and strengthen protective properties.  Once again, advances in weaponry deemed these early versions of body armor as being ineffective for protective use.
 
By World War II, flak jackets were in wide use within the military. While flak jackets were able to provide a level of protection against penetration from smaller arms munitions, they were completely ineffective if the wearer was faced with the treat of a rifle or higher velocity hand pistol. 
 
Modern Body Armor
 
By 1960 the discovery of new fiber weaves meant that researchers were able to create a real, light-weight concealable body armor that was truly bullet-resistant. These fibers could be woven into lightweight fabrics in such a way that helped to disperse the massive energy received from a projectile attack and help the wearer to avoid penetration. Research continued into the 1970s bringing further development of body armor until Dupont's Kevlar ballistic fabric woven into the fabric of early prototypes brought about a breakthrough in body armor technology. This new form of bulletproof vest was an effective lightweight body armor that was bullet resistant as well as light enough for military and law enforcement staff to wear full time.
 
Since that time, research and development of further protective qualities in bulletproof vests has continued to include waterproofing and also incorporating differently weaved fibers along with further layers of fabrics to also reduce the damage caused by blunt trauma.