DSL is a network access technology. It transforms a traditional phone line into a high-speed digital link to provide broadband Internet access. It uses special modems encode the data and then transmit it over an unused frequency on the phone line. With DSL you have a stable Internet connection that allows you to host your own Web site, connect branch offices of a small business, and to surf the Internet faster at any time of the day or night.
Cable modems are DSLs' closest competitors.
They rely on much of the same technology and provide similar service. Both cable and DSL use special modems and Ethernet cards for the same type of always-on connection. People prefer using DSL instead of traditional dial-up modems becuase DSL is much faster. Unlike DSL, cable modem users share lines. The more people connected to the line, the slower the connection speed will be.