3G refers to the third generation of mobile telephony technology. The third generation, as the name suggests follows two earlier generations, the 1G (80's) and 2G (90's).
The International Telecommunications Union (ITU) defined the third generation (3G) of mobile telephony standards IMT-2000 to facilitate growth, increase bandwidth, and support more diverse applications. For example, GSM could deliver not only voice, but also circuit-switched data at speeds up to 14.4 kbps. But to support mobile multimedia applications, 3G had to deliver packet-switched data with better spectral efficiency. at far greater speeds.