4G is the fourth generation of mobile phone technology. It follows on from the existing 3G (third generation) and 2G (second generation) mobile technology.
2G technology launched in the 1990s and was capable of making digital phone calls and sending texts. Then 3G came along in 2003 and made it possible to browse web pages, make video calls and download music and video on the move.
4G technology builds upon what 3G offers, but does everything at a much faster speed.