FRET technique provides a more precise way to measure the distance between two chromophores, called a donor-acceptor pair. The ability to measure the relative proximity of the molecules more precisely provides a better understanding of the physical interactions between protein partners involved in a typical bio-molecular process. This technique is also referred to as FRET imaging. FRET stands for ‘fluorescence resonance energy transfer’.  

FRET technique is highly distance-dependent. One of the most critical requirements for FRET to occur is that the donor and acceptor molecules must be in close proximity to each other, ideally less than 10 nanometers.