This book describes MEMS technology and demonstrates how MEMS allows miniaturization, parallel fabrication, and efficient packaging of optics, as well as integration of optics and electronics. It shows how the characteristics of MEMS enable practical implementations of a variety of applications, including projection displays, fiber switches, interferometers, spectrometers. The book goes on to describe the phenomenon of Photonic crystals (nanophotonics) and demonstrate how Photonic crystals enable synthesis of materials with optimized optical characteristics and allow control over optical fields over sub-wavelength distances, leading to devices with improved scaling and functionality compared to traditional optics. The book concludes with a discussion of the need for the combination of MEMS and Photonic crystals by demonstrating that practical photonic-crystal devices leverage MEMS technology for integration and packaging.