Some basic Real-Time PCR terms and their definitions are:
Amplification plot – Plot of fluorescent signal versus cycle number.
Baseline – The initial cycles of PCR where there is little to no change in fluorescence.
Threshold – The arbitrary level of fluorescence used for Cq determination. Should be set above the baseline and within the exponential growth phase of the amplification plot.
Cq (quantification cycle) – The fractional cycle number where fluorescence increases above the threshold. Also referred to as Ct (threshold cycle) or Cp (quantification cycle).
R – Reporter signal.
Rn – Normalized reporter signal.
?Rn – Baseline subtracted normalized reporter signal.
Slope – Indicates the efficiency of the reaction. With 10-fold dilutions, a slope of -3.32 indicates a perfect doubling of product per cycle (100% PCR efficiency).
R2 – Reports the linearity of the standard curve.