A set top box (STB) is a digital box that takes signals from your TV aerial, cable, satellite or broadband connection and converts them into a format that can be displayed on your television.
It handles certain actions like the user changing channels, retuning for new channels, sending the right type of signal required for the TV or home cinema system, and so on.
A HD-ready set top box will be able to receive both high definition and regular broadcasts, as available.
Some set top boxes also include digital video recorder (DVR) — also known as a personal video recorder — on which programmes can be recorded onto a hard drive. It may also be possible to pause, rewind and fast-forward live TV. Many STBs with this functionality have dual tuners. This makes it possible to record two separate channels at once, or watch one channel while recording another.
Many STBs are provided for free, or very low cost, when a consumer subscribes to a particular package such as Sky HD or BT Vision. More often than not, these boxes feature proprietary hardware or software which means they can only be used with one service provider.