A PCR test, or Polymerase Chain Reaction test, is a laboratory technique used to detect the presence of specific genetic material from an organism, such as a virus. It is commonly used to diagnose infections, including COVID-19. The test works by amplifying small amounts of DNA or RNA, making it easier to identify the target genetic material. During a PCR test, a sample is usually collected from a person's nose or throat using a swab. The sample is then processed in a laboratory, where it undergoes cycles of heating and cooling to replicate the genetic material. If the target genetic material is present, it can be detected and confirmed.