Fast Ethernet, which is specified in IEEE 802.3u, offers 100 Mbps. Fast Ethernet is a modern version of Ethernet and is often used in LAN backbone networks today (that is 1999), but is still not so commonly used for clients.
Gigabit Ethernet over fiber, is specified in IEEE 802.3z, offers 1000 Mbps. Gigabit Ethernet is not so common today (that is 1999). Gigabit Ethernet is only used in LAN backbone networks because it is expensive and there is not any need today for so high bandwidth to clients.
Gigabit Ethernet over twisted pair cable, is specified in IEEE 802.3ab, offers 1000 Mbps. This standard is not fully specified today, that is in the spring 1999. Gigabit Ethernet is the future of LAN development, because Ethernet is simple, reliable and will become cheap.
Token ring as specified in IEEE 802.5 offers 4 and 16 Mbps. The use of token ring technology is diminishing even though a new standard, called high speed token ring, offering 100 Mbps, has been specified.