Polymerase chain reaction, or PCR, is a technique that scientists use to rapidly make millions of copies of deoxyribonucleic acid, or DNA, which is the genetic material found inside every living organism. Kary Mullis, who shared the 1993 Nobel Prize in Chemistry for his contributions to PCR, developed the idea for its underlying biochemical mechanism in the early 1980s while working at Cetus Corporation, a company in Emeryville, California, that used biology to create tools for medical treatments, including cancer. Over the next several years, Mullis and his Cetus colleagues developed the technology, publishing the first study to reference PCR in the journal Science in 1985. Cetus scientists further enhanced PCR by adding Taq polymerase, an enzyme that helps copy DNA and remains stable at high temperatures. Prior to the development of PCR, researchers used slow, difficult methods to study small amounts of DNA. PCR facilitated the rapid and affordable amplification of DNA, helping with tasks like diagnosing diseases, solving crimes, and testing food and water for bacterial contamination.