Quantitative PCR, or qPCR, is a laboratory technique used to amplify and quantify DNA. It allows scientists to measure the amount of a specific DNA sequence in a sample, providing insights into gene expression, pathogen detection, and genetic variations. The process involves repeated cycles of heating and cooling, which help to separate the DNA strands and replicate them. During qPCR, a fluorescent dye binds to the DNA, enabling real-time monitoring of the amplification process. As the DNA quantity increases, the fluorescence intensity rises, allowing researchers to determine the initial amount of DNA in the sample. This technique is widely used in research, clinical diagnostics, and forensic science.