The signal source might be an Ethernet cable, a satellite dish, a coaxial cable (see cable television), a telephone line (including DSL connections), broadband over power lines (BPL), or even an ordinary VHF or UHF antenna. Content, in this context, could mean any or all of video, audio, Internet web pages, interactive video games, or other possibilities.
Satellite and microwave-based services also require specific external receiver hardware, so the use of set-top boxes of various formats has never completely disappeared. Set-top boxes can also enhance source signal quality.