The advent of fluorescent proteins and the continued development of novel fluorescent probes have put fluorescence microscopy at the center of life science research. Fluorescence microscopes range from relatively straight-forward wide-field microscopes to highly specialised spectral-imaging confocal microscopes. Confocal laser scanning microscopes (LSM) are used to improve fluorescence image quality by eliminating out-of-focus fluorescence and for 3D imaging using software reconstruction. Spinning disk confocal microscopes offer the advantage of video rate (30 frames per second) imaging with charge-coupled device (CCD) cameras. For live cell imaging at these speeds, 3D structures can be imaged on the subsecond time scale with the added benefit of reduced photobleaching/phototoxicity. Programmable array microscopes and line scanning microscopes are available and offer similar advantages to spinning-disk confocals. Finally, multi-photon microscopes use infrared light, which readily penetrates up to 600 μm, allowing deep tissue imaging in living animals.