MEMS (MicroElectroMechanical Systems) are a new frontier in miniaturization. Optics and MEMS have a natural synergism. On the one hand, optical techniques are basic to the manufacturing of MEMS. On the other hand, a wide variety of MEMS have already been demonstrated to produce, manipulate or detect optical radiation. The "optical" range of wavelengths is from 0.2 micrometers in the ultraviolet to 12 micrometers in the far infrared region. Entire optical systems with volumes on the order of 1 cm3 have been demonstrated. This review of optics and MEMS begins with the use of optical techniques to make MEMS. Then several techniques to measure the small motion of dynamic MEMS surfaces are described. Optical MEMS sources, optics are detectors are reviewed in turn. Then, a survey of salient optical MEMS applications follows. It is likely that MEMS will be very important commercially in the display and optical fiber communications sectors, among others. Design challenges, and the status of commercially-available software germane to the design of optical MEMS, and a short study of MEMS patents are given in two appendices. It is concluded that there are great opportunities for both new technology and new applications in this arena.