Cathode ray tubes are a vacuum tube with an electron gun at the back. The gun shoots electrons through the vacuum onto a screen which creates images. Thick screens that predate flat-screen televisions and computer monitors are cathode ray technology.
Background
German scientists Julius Plücker and Johan Hittorf discovered cathode-ray tubes. Hittorf noticed a negative electrode, called a cathode, cast shadows on the glowing wall of a tube. In 1980, Arthur Schuster showed magnetic fields could control the rays. By 1897, J.J. Thomson measured the mass of cathode rays showing they were smaller than atoms. Electrons is the name eventually settled on for them.
Ferdinand Braun found that coating the inside of the front of the tube with phosphorous made it glow brighter. Finally, Americans Harry Weinhart and John Johnson of Western Electric created the first commercial CRT in 1922.
Eventually, countless CRT sub-types were invented. There were military uses but the most obvious use was television. Vladimir Zworykin of RCA created a better tube that he claimed is the first television. The entry television goes into more detail about that.
CRT’s Evolve
There were countless improvements to CRT’s. Over the decades they increased steadily in size and shrunk slightly in thickness. Color tubes included three beams aimed at three layers of phosphorous. When combined they created a color image.
CRT televisions worked but they were mechanical devices, even when driven by a digital display like a computer monitor. Due to imperfections in the manufacturing process, small magnets were glued to the outside of a tube to adjusted the beam.
Even the slimmest CRT’s were still heavy and used a lot of electricity. Over time, flat-screen technologies including plasma, LED backlights, and OLED’s replaced CRT’s.
“If you absolutely must have the most authentic, optimal experience and don’t mind having a giant, heavy fucking brick of a television, then yes.”
Anonymous internet commentator on using CRT’s to play old game consoles.