The polymerase chain reaction (PCR) is a laboratory technique used to amplify specific segments of DNA. It allows scientists to create millions of copies of a particular DNA sequence, making it easier to study and analyze. PCR involves repeated cycles of heating and cooling, which separate the DNA strands and enable the binding of short DNA primers that target the desired sequence. During the process, an enzyme called DNA polymerase synthesizes new DNA strands by adding nucleotides to the primers. This cycle is repeated multiple times, exponentially increasing the amount of DNA. PCR is widely used in various fields, including genetics, forensics, and medical diagnostics.