always-on - Computer Definition
Referring to a continuous Internet connection. Such a connection is always available from the computer through the service providers central office (CO) or headend and to the Internet. Therefore, there are no dial-up delays such as those experienced when using a conventional modem to establish a circuit-switched connection to the Internet over the public switched telephone network (PSTN). The term generally is used to describe xDSL or cable modem services. See also cable modem, circuit-switched, CO, headend, Internet, modem, PSTN, and xDSL.
A system that is online and ready to go 24 hours a day. Nothing has to be turned on or dialed up in order to use it. DSL and cable modems are examples of always-on technologies. ISDN is a dial-up technology, but the process is extremely fast and gives the appearance of an always-on connection.