Polymerase Chain Reaction (PCR) is a laboratory technique used to amplify specific segments of DNA. By repeatedly heating and cooling the DNA, PCR enables the duplication of a targeted sequence, producing millions of copies. This process involves three main steps: denaturation, annealing, and extension, which are facilitated by a special enzyme called DNA polymerase. PCR is widely used in various fields, including genetics, forensics, and medical diagnostics. It allows scientists to analyze small amounts of DNA, making it easier to study genetic disorders, identify pathogens, and perform DNA fingerprinting in criminal investigations.