ArtNet is DMX over Ethernet (DOE) and was developed by Artistic Licence. ArtNet supports up to 256 universes over one piece of CAT-5 cable compared to one universe over a DMX cable.
USITT DMX512 is well known in the entertainment industry because it is the industry standard for controlling dimmers and automated lighting fixtures (moving lights). The electrical standard of DMX512 is RS485 which is as superset of RS422 which almost the same as RS232, well known as serial port on a PC. Ethernet is the electrical standard that transports data based on TCP/IP, well known as a standard in todays internet. ArtNet is based on TCP/IP and uses UDP Packets.
The protocol that is used is published on the Artisic Licence website and is available to anyone to use. Major vendors such as ADB, MA Lighting, High End, Avolites, Martin Professional, ChamSys and others are now using this protocol. More and more fixtures are now appearing with RJ45 connectors for use with ArtNet. Companies like Enttec and others are suuplying DOE interfaces and even some free lighting control programs such as FreeStyler support ArtNet.