A somewhat vague term used to describe wireless mobile radio technologies that offer faster data rates than 3G (third generation) technologies.
4G networks are also more data-centric and based on standard Internet technologies such as IP. Voice service, if provided over the 4G network, is typically provided using a special form of VoIP.
The most common technology worldwide recognized as 4G is LTE.
A less-common 4G technology is WiMAX, which Sprint initially deployed for 4G, before backtracking and deploying LTE instead.
Some carriers (service providers / network operators) - including T-Mobile and AT&T - have used the term "4G" to refer to upgraded 3G networks that provide near-4G data speeds even they are based on 3G technology. HSPA+ technology is the 3G upgrade that enables these faster speeds.