3G service is high-speed access to data and voice services, made possible by the use of a 3G network. A 3G network is a high-speed mobile broadband network, offering data speeds of at least 144 kilobits per second (Kbps).
For comparison, a dial-up Internet connection on a computer typically offers speeds of about 56 Kbps. If you've ever sat and waited for a Web page to download over a dial-up connection, you know how slow that is.
3G networks can offer speeds of 3.1 megabits per second (Mbps) or more; that's on par with speeds offered by cable modems. In day-to-day use, the actual speed of the 3G network will vary. Factors such as signal strength, your location, and network traffic all come into play.