A set-top box (STB), also known as a cable box or receiver and historically television decoder or a converter, is an information appliance device that generally contains a TV-tuner input and displays output to a television set and an external source of signal, turning the source signal into content in a form that can then be displayed on the television screen or other display device. They are used in cable television, satellite television, and over-the-air television systems as well as other uses.

A cable converter box or television converter box is an electronic tuning device that transposes/converts channels from a cable television service to an analog RF signal on a single channel, usually VHF channel 3 or 4, or to a different output for digital televisions such as HDMI.