At optical wavelengths there are a wide variety of techniques to detect interference fringes. Because detectors in the visible/IR are energy detectors, the fringe amplitude and phase must be encoded in some manner. Two fundamentally different methods are temporal and spatial encoding. This paper briefly describes the various techniques that have been used in operational interferometers along with their advantages and disadvantages. Several fringe detectors for next-generation interferometers will also be described. These fringe detectors often combine multiple functions, such as spectroscopy and multi-beam combination.