A Set Top Box is a device that enables a TV set to become a user interface to the video streaming and also enables a TV set to receive & decode digital TV (DTV) broadcasts. The user interface usually is through the Electronic Program Guide for various selections. A Set-Top Box is necessary for TV viewers who wish to use their current analog TV sets to receive digital broadcasts.
Modern day Set Top Boxes offer a wide variety of features Like High Definition Video, 5.1 Channel Audio, Dolby Sound, Multi Lingual Audio among other features. More sophisticated Set-top boxes contain a hard drive for storing recorded television broadcasts, for storing live TV broadcast to view programs later. Some Service providers also provide Value Added Service Like Movie on Demand, Internet connectivity, interactive Services & Games.
In India, typically the DVBS / DVBS - 2 DTV standard is followed. The services are available through satellite and through cables also.