This write-up is dedicated to czeano
ATM is a packet-switching technology that uses 53-byte cells to support voice, video, data, and images. These cells, of which 48 bytes are data, allow for reduced delay and variance of jitter. It is broken up into four layers: Physical layer, Transmission Convergence layer, ATM layer, and ATM Adaption layer (AAL). The details of these layers and their sub-layers would require a much longer write-up, and I'm simply too busy playing Grim Fandango right now.
ATM can be used as a high-speed underlying technology for Frame Relay on campus networks, for example, or to interconnect high-speed LANs. ATM switches offer connection speeds up to OC-12 (622 Mbps) and desktop connections up to OC-3 (155 Mbps).
The ATM Forum was established in 1991, and you can find all kinds of ATM information at www.atmforum.com.
As a side note, whenever an ATM problem came up at work in the year 2000, even the best of us freaked out, because only a few clients recently had it implemented: "Do you know anything about ATM?" "No." "Do you know anything about ATM?" "No." And so on. Good times...