Optical super-resolution diagnostics have revolutionised the field of imaging by visualising structures beyond the previously established diffraction and information resolution limits established by [1]-[3]. They have enabled the visualisation of structures at the nanoscale, changing the field of microscopic imaging for a variety of fields, including biomedical imaging, material science and nanotechnology. This paper presents an overview of several current super-resolution diagnostic techniques, describing the different optical limitations and resolutions as well as a discussion of the new knowledge that can be unlocked by the application of these technologies in areas of material and biomedical science.