E-paper, also known as electronic paper or electronic ink display, was first developed in the 1970s. It reflects light like ordinary paper and is more comfortable to read than backlit displays. E-paper is constructed of a front plane made of electronic ink microcapsules and a back plane of circuitry. When voltage is applied, particles inside the microcapsules move and the surface appears white or black. Key technologies include Gyricon, electrophoretic displays, and electrowetting. E-paper has advantages of low power consumption, wide viewing angle, and flexibility but lower refresh rates than LCDs. It is used in e-readers, mobile phones, signs, and other applications.