Old TV components refer to the technology used in televisions prior to the introduction of flat-screen displays. The most common components were the TUBE, triode, and CRT. A TUBE was a vacuum-sealed glass container that contained a filament and electrodes, which allowed electricity to flow through it. A triode was an electronic device consisting of three electrodes, which was used to amplify signals. Finally, a CRT (Cathode Ray TUBE) was a vacuum TUBE containing an electron gun and a fluorescent screen, which was used to display images.