Polymerase chain reaction (PCR), a revolutionary molecular tool, has transformed genetic studies by facilitating rapid DNA amplification. The PCR process relies on several key components: a DNA template or cDNA, two primers, Taq polymerase, nucleotides, and a buffer. These elements collectively facilitate the amplification process, which comprises three stages: denaturation, annealing, and extension. These stages are repeated in cycles to exponentially amplify the target DNA sequence. Furthermore, the power of PCR lies in its ability to generate exponential copies of target DNA in a remarkably short period. Moreover, various PCR techniques are available, encompassing traditional approaches like quantitative PCR, reverse transcription PCR, and nested PCR, as well as innovative methods such as extreme PCR, inverse PCR, and touchdown PCR. These techniques are extensively utilized in molecular, biological, and medical research laboratories for both research and diagnostic applications. This review explores a comprehensive overview of PCR, covering its history, underlying principles, and diverse applications in diagnostics, research, and drug development.