• Asymmetric digital subscriber line (ADSL) is a type of digital subscriber line (DSL) technology, a data communications technology that enables faster data transmission over copper telephone lines than a conventional voice band modem can provide.

• ADSL (Asymmetric Digital Subscriber Line) is a technology for transmitting digital information at a high bandwidth on existing phone lines to homes and businesses.

• Unlike regular dialup phone service, ADSL provides continuously-available, "always on" connection.

• ADSL differs from the less common symmetric digital subscriber line (SDSL).

• In ADSL, Bandwidth and bit rate are said to be asymmetric, meaning greater toward the downstream than upstream.

• ADSL is generally offered at downstream data rates from 512 Kbps to about 6 Mbps.

• Providers usually market ADSL as a service for consumers for Internet access for primarily downloading content from the Internet, but not serving content accessed by others.

• ADSL works by using the frequency spectrum above the band used by voice telephone calls.

• With a DSL filter, often called splitter, the frequency bands are isolated, permitting a single telephone line to be used for both ADSL service and telephone calls at the same time.

• ADSL is generally only installed for short distances from the telephone exchange, typically less than 4 kilometers.

• At the telephone exchange, the line generally terminates at a digital subscriber line access multiplexer (DSLAM) where another frequency splitter separates the a frequency band that might interact voice band signal for the conventional phone network.

• Data carried by the ADSL are typically routed over the telephone company's data network and eventually reach a conventional Internet Protocol network.

• ADSL communication is full-duplex. Full-duplex ADSL communication is usually achieved on a wire pair by either frequency-division duplex (FDD), echo-cancelling duplex (ECD), or time-division duplex (TDD).