Quantitative polymerase chain reaction (qPCR) is a commonly used molecular biology technique that allows for the quantification of DNA or RNA in a given sample. It is a highly sensitive and specific method that measures the amount of a particular nucleic acid sequence in a sample by amplifying and detecting it using fluorescent dyes. QPCR is widely used in research, diagnostics, and forensic analysis to study gene expression, detect pathogens, and monitor genetic mutations, among other applications. It is a powerful tool for studying the genetic material of organisms and has revolutionized many fields of biological research.