An optical switch is a device used to route optical signal from one line to another. Optical switches are different from electronic switches that work on electronic signals, as they are acts on photons instead. The most common type of optical switch is the micro-electromechanical system (MEMS). MEMS switches move mirrors within a fiber to direct the signal. These types of switches can be operated in milliseconds, making them suitable for high performance applications such as telecommunication networks. Other types of optical switches include liquid-crystal switches, acousto-optic switches, and diffractive optical switches. These switches use different types of materials to redirect light, but the basic principle of directing and switching optical signals is the same.