Digital PCR (dPCR) enables precise, highly sensitive quantification of nucleic acids. Traditional PCR is an end-point analysis that is semi-quantitative at best — the amplified product is detected by agarose gel electrophoresis after the reaction is finished. Real-time PCR (or qPCR) uses fluorescence-based detection to allow the measurement of accumulated amplified product as the reaction progresses. qPCR requires normalization to controls (either to a reference or to a standard curve), allowing only relative quantification. Furthermore, variations in amplification efficiency may affect qPCR results. Digital PCR builds on traditional PCR amplification and fluorescent-probe–based detection methods to enable highly sensitive absolute quantification of nucleic acids without the need for standard curves. This section provides an overview of digital PCR technology and methods and its application.