A Cathode Ray Tube (CRT) is an older display technology that was commonly used in television sets and computer monitors before the advent of flat-panel displays like LCDs and LEDs. A CRT works by firing a stream of electrons from an electron gun (the cathode) towards a phosphorescent screen, which emits light when struck by the electrons, creating an image. The inside of the screen is coated with phosphor dots that glow red, green, or blue when hit by the electron beam, and by controlling the intensity and position of the beams, the CRT can display a full-color image.
CRT monitors are known for their bulky size and significant weight, as the tube itself is large and requires a vacuum to operate. Despite their size, CRTs were praised for their high image quality, color accuracy, and fast refresh rates. However, they have largely been replaced by more compact, energy-efficient, and higher-resolution flat-panel displays in modern devices.