GSM (Global System for Mobile Communications, originally Groupe Spécial Mobile), is a standard set developed by the European Telecommunications Standards Institute (ETSI) to describe technologies for second generation (2G) digital cellular networks. Developed as a replacement for first generation (1G) analog cellular networks, the GSM standard originally described a digital, circuit switched network optimized for full duplex voice telephony. The standard was expanded over time to include first circuit switched data transport, then packet data transport via GPRS (General Packet Radio Services). Packet data transmission speeds were later increased via EDGE (Enhanced Data rates for GSM Evolution) referred as EGPRS. The GSM standard is more improved after the development of third generation (3G) UMTS standard developed by the 3GPP. GSM networks will evolve further as they begin to incorporate fourth generation (4G) LTE Advanced standards. "GSM" is a trademark owned by the GSM Association.

Early European analog cellular networks employed an uncoordinated mix of technologies and protocols that varied from country to country, preventing interoperability of subscriber equipment and increasing complexity for equipment manufacturers who had to contend with varying standards from a fragmented market. The work to develop a European standard for digital cellular voice telephony began in 1982 when the European Conference of Postal and Telecommunications Administrations (CEPT) created the Groupe Spécial Mobile committee and provided a permanent group of technical support personnel, based in Paris. In 1987, 15 representatives from 13 European countries signed a memorandum of understanding to develop and deploy a common cellular telephone system across Europe. The foresight of deciding to develop a continental standard paid off, eventually resulting in a unified, open, standard-based network larger than that in the United States.