ADSL is a broadband connection technology which utilises existing copper wired telephone networks. ADSL uses a wide range of frequencies over an existing telephone line to deliver much higher speeds than your standard 56k modem (between 10 and 140 times faster). It is also possible to use your phone while online.
One of the cool features of DSL is that you do not need to have a ‘special’ line installed – you can be surfing the internet and talking to someone on the phone all on the same line. This is because DSL uses a high frequency that does not effect the normal use of your phone.
ADSL (Asynchronous Digital Subscriber Line) is the same as SDSL, but the upstream bandwidth is smaller than the downstream. This version of DSL is generally more affordable than SDSL.