Asymmetric Digital Subscriber Line technology sends and receives data at high speeds over copper telephone lines. The telco guarantees 384Kbps on an ADSL line.
Higher performance varies on line conditions and distance from the switch.
ADSL requires a special modem designed for the higher speeds that connects to a telephone jack similar to a conventional modem. Cable modems, like ADSL are a faster alternative to conventional 56k connections. Unlike ADSL, cable modems share bandwidth with all users in a particular area. If a user on the same block is downloading large files, all users will experience slower speeds. With ADSL, each user is provided with their own dedicated connection, thus avoiding a performance hit seen with a cable modem setup.