crt

CRT stands for cathode ray tube. It was a type of TV that was used in the past. CRT TVs looked like big boxes with a screen and they used tubes to create pictures. Inside these tubes there were beams of "cathode rays" that were shot at the back of the inside of the TV and bounced off phosphor dots. The phosphor dots were like tiny coloured dots that glowed and created different kinds of colours. That way, the rays created a picture and this is what you saw when you watched TV. CRT TVs have not been used for many years now, since there are new technologies that create much better TV images.