“Seeing is believing” – this saying is certainly true for vision-guided human beings like ourselves. If we witness something unusual with our own eyes, we most likely believe it to be true. A scientific hypothesis can be probed with an experiment and depending on what we see, we conclude that the hypothesis is correct or not. Unfortunately, we cannot see the molecules in the living cell with the naked eye, because they are too small and usually colourless. Thankfully, nature has provided us with molecules which glow when excited by light (e.g. in jellyfish). The energy of the stimulating light catapults a fluorescent dye molecule into a state of high energy and it gets rid of it by emitting light itself (glowing). We can attach a fluorescent dye to a molecule that we would like to study; exciting the fluorescence emitting molecule will give a signal that we can see. The experimental technique of fluorescence labelling has become invaluable in biological research and is used in many of our research projects on a routinely bases.