How does digital PCR differ from quantitative PCR?

Digital PCR (dPCR) partitions the sample into thousands of individual reactions, each containing zero, one, or a few template molecules. After endpoint PCR, positive partitions are counted, and absolute quantification is calculated using Poisson statistics. Unlike qPCR, dPCR provides absolute quantification without standard curves, is more precise for low copy number detection, is less affected by PCR inhibitors, and enables detection of rare variants. Platforms include droplet digital PCR (Bio-Rad, RainDance) and chip-based systems (Fluidigm, Thermo). Applications include rare mutation detection, copy number variation, viral load monitoring, and gene expression in limited samples.