qPCR, or quantitative Polymerase Chain Reaction, 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, making it useful for various applications, including gene expression analysis and pathogen detection. The process involves repeated cycles of heating and cooling, which separate the DNA strands and enable the synthesis of new DNA. By using fluorescent dyes or probes, researchers can monitor the amplification in real-time, providing precise measurements of DNA concentration throughout the experiment.