The emergence of novel fluorescent DNA labeling techniques in the past few years has enabled the analysis and detection of PCR products in real-time and has consequently led to the widespread adoption of real-time RT-PCR for the analysis of gene expression. Not only is real-time RT-PCR now the method of choice for quantification of gene expression, it is also the preferred method of obtaining results from array analyses and gene expressions on a global scale. Currently, there are four different fluorescent DNA probes available for the real-time RT-PCR detection of PCR products: SYBR Green, TaqMan, molecular beacons, and scorpion probes. All of these probes allow the detection of PCR products by generating a fluorescent signal. While the SYBR Green dye emits its fluorescent signal simply by binding to the double-stranded DNA in solution, the TaqMan probes', molecular beacons' and scorpions' generation of fluorescence depend on Förster Resonance Energy Transfer (FRET) coupling of the dye molecule and a quencher moiety to the oligonucleotide substrates.