Confocal laser scanning microscopy (CLSM or LSCM) obtains high-resolution optical images by acquiring images point-by-point and reconstructing them with a computer, allowing three-dimensional reconstructions of topologically complex objects. These microscopes, found in biomedical clinical and research laboratories, are used in sensitivity demanding applications. There are two main subcategories- single point, often used in tissue slice imaging, and array scanning- often used for live cell imaging. The major optical microscopy vendors—Olympus, Nikon Instruments, Leica Microsystems and Carl Zeiss MicroImaging—offer confocal microscopes. When choosing a system, consider the applications such as live-cell imaging or fixed-tissue sections, FRET, multiphoton microscopy or super-resolution imaging. Expanding into different types of imaging requires upgradability. Also important in system selection is ease of use, availability of maintenance contracts and access to technical support.