Nanoscopy is the next-generation fluorescence microscopy family which allow us to see not only down to the microscale, but even to the nanoscale. Being techniques utilizing fluorescence means that the images obtained have a high specificity to specific molecules. The main usage is in life sciences and biological imaging, where biological molecules in the cell can be labelled with specific probes, which in turn can be imaged. The resulting image represents the cellular distribution of the biological molecule.STED, short for stimulated emission depletion, is a type of nanoscopy which in practice is similarly executed as the more traditional confocal fluorescence microscopy. In confocal microscopy, one laser beam is focused and used to excite the probes of interest. The resolution achieved is entirely limited by the diffraction limit of light, a physical limit affecting how well you can focus light, which was long thought to be impassable. In STED nanoscopy, the setting is similar but with an additional laser beam inducing stimulated emission from the fluorescent molecules. By shaping the second laser beam not as a focused spot, but instead as a donut, means that you can spatially affect only the outer parts of the diffraction-limited excitation spot. In this way, the molecules allowed to fluoresce come from a much smaller spot than the diffraction-limited excitation spot, and through that you can break the physical limits imposed on fluorescence microscopy. The achievable resolution is theoretically unlimited but practically up to 10-fold better than in traditional fluorescence microscopy, down to 20 nm, meaning that one can observe cellular processes with a much higher precision than before, and discover processes previously hidden by the diffraction limit.