WHAT IS ADSL?
ADSL (Asymmetric Digital Subscriber Line, or DSL for short) is a high-speed Internet access service that utilizes existing copper telephones lines to send and receive data at speeds that far exceed conventional dial-up modems.
The fastest dial-up modems are rated at 57 kilobits per second, and usually operate at about 53 Kbps under good conditions. By comparison, ADSL allows datastream speeds from 1.5 to 8 megabits per second, depending on the grade of ADSL service purchased.
ADSL uses standard telephone lines to transmit upstream and downstream data on a digital frequency, which sets these datastreams apart from the analog signals telephones and fax machines use. Because the ADSL signal is operating on a different frequency, the telephone can be used normally, even when surfing the Web with ADSL service. The only requirement will probably be inexpensive DSL filters on each phone or fax line, to remove any "white noise" on the line that might be generated from ADSL service.
The "asymmetric" in ADSL refers to the fact that the downstream data rate, or the data coming to your computer from the Internet, is traveling faster than upstream data, or the data traveling from your computer to the Internet. Upstream data rates are slower because Web page requests are fairly minuscule data strings that do not require much bandwidth to handle efficiently.
WHY WOULD I NEED ADSL?
ADSL is an "always on" service, meaning that as long as your computer is powered on, it will automatically stay connected to the Internet unless you manually disconnect via software or hardware. ADSL is especially suited for gamers, CAD use, streaming multimedia and downloading large files. Family members can share ADSL accounts, with a basic monthly fee covering several mailboxes.
Unlike dial-up service, which stipulates only one session be instigated at a time, multiple members can be using ADSL service simultaneously on various computers in the house without violating policy.
WHAT DO I NEED TO USE ADSL?
Firstly if you don't have regular land line phone, more people are ditching their regular phones to get cell phones, then a cable modem would be your first choice. DSL requires you to have a pre existing phone line. With DSL your phone line has to "qualify" for the DSL service. In plain english this means that you have to be a certain maximum distance from the telephone exchange to get DSL. If you are past the maximum allowed distance then you won't be able to get DSL and in some cases it's not until the technician has physically come around to your house or business and run a line test that you know you will qualify.
The ADSL service requires an Internet service provider (ISP), and ADSL modem or router.