SYBR Green is one of the most commonly used fluorescent dyes in qPCR. It binds to double-stranded DNA molecules by intercalating between the DNA bases. Once intercalated to DNA, SYBR Green becomes less mobile, causing its energy to be released as fluorescence. Therefore, the fluorescence intensity is directly associated with the concentration of double-stranded DNA, which can be measured at the end of each amplification cycle to determine the PCR progress.