FRET

FRET, or Förster Resonance Energy Transfer, is a technique used to study the closeness of two molecules. It involves two fluorescent molecules: a donor and an acceptor. When the donor molecule is excited by light, it can transfer energy to the nearby acceptor if they are within about 1–10 nanometers, causing the acceptor to emit light. This transfer only happens when the molecules are very close, making FRET a sensitive way to detect molecular interactions or changes in shape, movements, or distances at a very small scale in biological systems.