Helps to prevent fatal/harmful injury caused by a severe cut and/or tear by a sharp object such as a knife.
More Detailed Answer:
Stab and puncture resistant armors are made from a variety of materials. The most commonly used materials are made from extremely strong fibers, which can be either woven or laminated together. Other materials used are metals and composites. As the threat impacts the armor, the materials either deflect the threat, or due to their very high level of cut and/or tear resistance, they 'stretch' and the impact forces are dissipated over a larger area of the armor