Fluorescence microscopy is a microscopy technique that uses fluorescence, which is induced using fluorophores, as opposed to absorption, scatter, or reflection. A fluorophore (or fluorochrome) is a fluorescent dye used to mark proteins, tissues, and cells with a label for examination by fluorescence microscopy. A fluorophore works by absorbing energy of specific wavelengths, commonly referred to as the excitation range, and re-emitting that energy in another specific wavelength region, referred to as the emission range.