Kevlar is a high-strength, lightweight synthetic fiber that is used in a variety of applications, including bulletproof vests. Kevlar is made from poly-paraphenylene terephthalamide, which is a polymer that is produced from terephthalic acid and p-phenylene diamine. Kevlar has a high tensile strength, which means that it can withstand a great deal of force before breaking. It is also very resistant to heat and chemicals. These properties make Kevlar ideal for use in bulletproof vests.