The TaqMan probe principle relies on the 5´–3´ exonuclease activity of "Taq" polymerase to cleave a dual-labeled probe during hybridization to the complementary target sequence and fluorophore-based detection. As in other quantitative PCR methods, the resulting fluorescence signal permits quantitative measurements of the accumulation of the product during the exponential stages of the PCR; however, the TaqMan probe significantly increases the specificity of the detection. TaqMan probes were named after the videogame Pac-Man ("Taq" Polymerase + PacMan = TaqMan) as its mechanism is based on the Pac-Man principle.