A cathode ray tube display (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 colors on the screen based on the electron beam's position. CRTs are known for their deep colors and wide viewing angles, but they are bulky and heavy compared to modern displays like LCD and LED screens. As technology advanced, CRTs became less common, replaced by lighter and more energy-efficient display technologies.