The work on GSM, a standardized European second-generation cellular system, was started in 1982 in order to prevent the fragmentation of the first-generation cellular market from continuing into the second generation. The goal was to define a system with open interfaces for Pan-European use that would offer the best compromise between a number of conflicting requirements, such as spectrum economy, high speech quality, low cost, and a large range of services. A broad outline of the novel features is presented, both concerning the architecture of the system and of the services offered, as well as the reasoning behind the more important choices. Finally, some views are presented concerning the future development of GSM and of the third-generation system, the co-called Future Public Land Mobile Telecommunication System, commonly referred to as FPLMTS.