What does FRET mean?

FRET is an abbreviation for Förster Resonance Energy Transfer or Fluorescence Resonance Energy Transfer. Förster Resonance Energy Transfer is named after Theodor Förster, the German scientist who contributed to the theoretical analysis and better understanding of the energy transfer between two light sensitive molecules or chromophores.

According to the Förster theory, FRET efficiency varies as the inverse sixth power of the distance between the two molecules.