General Packet Radio Service or GPRS is a digital mobile phone technology. It is considered as 2.5G, between the second and third generation. It provides high-speed data transfer. This technology is compatible only with GSM networks.
GPRS is basically an addition to enable packet based communications in the TDMA-based GSM system. Timeslots in GSM is normally allocated to create a circuit-switched connection, but the GPRS the timeslots are allocated to the packet-connection on a need-basis. This means that if no data is sent by a sender, the frequencies involved is free to be used by other senders.