Super-resolution is a term used to refer to methods that allow spatial discrimination of objects that are smaller than about 200 nm (0.2 microns). Two basic methods are used to achieve super-resolution. (1) Methods that constrain the illumination field used for fluorescence excitation or (2) methods that constrain the population of detectable fluorophores in the specimen. Notwithstanding these advances, light microscopy cannot yet deliver sub-nanometer spatial resolution comparable to electron microscopy. Techniques for correlative light and electron microscopy (CLEM) are therefore important for combining information obtained from these two contrast modalities.