The term
set-top box describes a device that connects to your
television and some
external source of signal, and turns what's in that signal into content on your screen.
The signal source might be a satellite dish, a cable (see
cable television), a phone line,
a DSL connection or maybe even an ordinary UHF/VHF antenna.
Content, in this context, could mean any or all of video, audio, internet pages, interactive games,
or a dozen other possibilities.