The polymerase chain reaction (PCR) is a laboratory technique used to amplify specific segments of DNA. By using short DNA sequences called primers, PCR can create millions of copies of a targeted DNA region in just a few hours. This process involves repeated cycles of heating and cooling, which separate the DNA strands and allow the primers to bind and initiate replication. PCR is widely used in various fields, including molecular biology, forensic science, and medical diagnostics. It enables researchers to analyze genetic material, identify pathogens, and even solve crimes by amplifying tiny amounts of DNA found at crime scenes.