A cathode ray tube display, commonly known as a CRT, is a technology used in older televisions and computer monitors. It works by firing electrons from a cathode through a vacuum tube, which then strikes a phosphorescent screen. This process creates images by illuminating different areas of the screen in various colors. CRTs were popular for many decades due to their ability to produce high-quality images and deep blacks. However, they have largely been replaced by newer technologies like LCD and LED displays, which are lighter, thinner, and more energy-efficient.