3G / 4G refer to the generation of mobile communication technology.
3G or third generation mobile networks mark the transition to mobile broadband. Initially they targeted a minimum consistent speed of 144kbps on the move, but now they have grown to offer even up to 4Mbps speeds for stationary users.
4G technology marks the next generation, and is used to refer to LTE, WiMax and other transmission technologies that enable even higher download speeds. 4G services still have limited spread and are concentrated in metro regions across the world.