Förster resonance energy transfer-what can we learn and how can we use it?

The present manuscript gives a short overview on Förster Resonance Energy Transfer (FRET) of molecular interactions in the nanometre range. First, its principle is described and a short historical overview is given. Subsequently some principal methods and applications of FRET sensing and imaging are described (with some emphasis on fluorescence lifetime imaging, FLIM), and finally two innovative FRET techniques are presented in more detail. Applications are focused on measurements of living cells.