A 100 MBps Ethernet standard specified to run over four pairs of category 3 UTP wires (known as voice grade, hence the "VG"). It is also called 100VG-AnyLAN because it was defined to carry both Ethernet and token ring frame types.
100BaseVG started in the IEEE 802.3u committee as Fast Ethernet. One faction wanted to keep CSMA/CD in order to keep it pure Ethernet, even though the collision domain problem limited the distances to one tenth that of 10baseT. Another faction wanted to change to a polling architecture from the hub (they called it "demand priority") in order to maintain the 10baseT distances, and also to make it a deterministic protocol. The CSMA/CD crowd said, "This is 802.3 -- the Ethernet committee. If you guys want to make a different protocol, form your own committee". The IEEE 802.12 committee was thus formed and standardised 100BaseVG. The rest is history.