Hardware device used to provide Internet access using the cable provided by a Pay TV service, such as Foxtel or Optus Vision.

One or more standard cable TV channels are used for the downstream bandwidth, which is shared by all the users in a cable loop, while the upstream uses special channels below the normal TV band.  Sharing of the upstream is achieved by careful control of the power level and TDMA (Time Division Multiple Access).

For more info on cable modems, try
(http://www.howstuffworks.com/cable-modem.htm Howstuffworks "How Cable Modems Work")
(http://www.cable-modems.org/tutorial/ Cable-Modems.org : Tutorial)