Photonic crystals are referred to as semiconductors for light and can control the flow of photons in microscopic space since semiconductors do the flow of electrons in ULSI(Ultra Large Scale Integration) circuits. Therefore, photonic crystals have attracted enormous attention due to their potential applications including channel-drop filters, nanolasers, optical waveguides and others that are required for the development of next-generation optical telecommunication devices and optical computers. Photonic crystal balls at micrometer scales can be also used as full-color pixel sources in the pioneering microdisplay devices. Here, we review fundamental concepts of photonic crystals, several approaches to fabrication of three-dimensional photonic crystals, and their potential application areas. In particular, we emphasize the colloidal self-assembly scheme that is the most attractive to chemical engineers among several synthetic methods.