Short for Switched Multimegabit Data Services,
a high-speed switched data communications service offered by telephone companies that enable organizations to connect geographically separate local-area networks (LANs)
into a single wide-area network (WAN)
. Prior to SMDS’s arrival in 1995, the only way to connect LANs was through a dedicated private line. This is still the way most WANs are connected, but SMDS is becoming an increasingly attractive alternative because it is more flexible and in many cases more economical.