Cable modems are devices that provide high-speed Internet access using cable television networks.

They are designed to work over TV lines. They are connected to the TV outlet for cable TV transmission and the operator connects a Cable Modem Termination System at the cable companys main office. The cable modem can be used for fast access to the World Wide Web.

Cable modems are available as an internal, external or set-top box device. An external cable modem is a small box that will have two cable connections, one to the cable wall outlet and the other to a computer through a standard 10Base-T Ethernet card. An internal cable modem is a PCI bus add-in card for a PC. They can only be used in desktop PCs. The set-top box is a cable modem in a cover, which supplies return channel through the Plain Old Telephone System.

Regular modems use a phone line to dial up and connect with another modem. Cable modems connect your computer to the Internet service provider by translating the networks information so it can be passed back and forth over the cable channel. Cable modems can plug directly into your computer via a USB connection or a network card in your computer. A network card is the hardware that allows you to communicate on a network. In the case of a cable modem connection, it allows your computer to talk with the cable modem. It takes the place of a regular modem in your computer. Just turn the computer on. With a cable modem, your connection is always on. This means that you do not need to dial in. Whenever your computer is on, you are on the Internet, automatically.

Cable modems vary in cost. Since there isn't a universal standard for them, you have to get a cable modem that works with your specific provider. There are many companies who are producing or have announced cable modem products. They include: 3Com, Bay Networks, Com21, General Instrument, Hayes, Hybrid Networks, Motorola, NEC, New Media Communication, neighborhood, Scientific Atlanta, Terayon, Toshiba, U.S. Robotics and Zenith.