DSL, or Digital Subscriber Line, is a high-bandwidth Internet connection that uses existing phone lines. It is a family of technologies that provides digital data transmission over the wires of a local telephone network. DSL originally stood for digital subscriber loop. In telecommunications marketing, the term Digital Subscriber Line is widely understood to mean Asymmetric Digital Subscriber Line (ADSL), the most frequently installed technical variety of DSL.

DSL service requires a DSL modem, which connects to the telephone wall jack and computer. The device acts as a modulator, translating the computer’s digital signals into voltage sent across the telephone lines to a central hub known as a Digital Subscriber Line Access Multiplier (DSLAM). In lay terms the DSLAM acts as a switchboard for local DSL clients, routing requests and responses between each client’s computer address and the Internet.

What is a DSL modem? A DSL modem is the device where the computer connects to in series with the telephone unit to be able to gain web access. They work similarly to Dial-Up modems, wherein the difference is in the use of a DSL line rather than Dial-up. Digital subscriber line providers usually provide the DSL modem when installing their DSL service at homes or business establishments. However, the customer can be given the choice of purchasing elsewhere as DSL modems are available in different models, with different transfer rates and type of connections. A device which enables the user to share the internet connection gained from having a Digital Subscriber Line is known as DSL router. A single home with multiple computers will be able to access the internet service simultaneously by using a high speed DSL router. Similar to DSL modems, DSL routers also come in various models, speed and range. Companies such as D-Link and Cisco are just some of the major business players on network hardware manufacturing.

Some of the differences between DSL and cable modem originate not with the technology itself but rather with the service provider. All other things being equal, factors like cost, reliability and quality of customer support for installation and maintenance issues can vary significantly from one provider to the next. Different Internet service providers sell connectivity to customers, usually through monthly service contract. More recently, wireless Internet service providers have emerged that offer Internet access through wireless LAN or wireless broadband networks. In addition to basic connectivity, many ISPs also offer related Internet services like email, Web hosting and access to software tools. Service providers advertise DSL speed in terms of bandwidth ratings. Bandwidth numbers advertised for residential DSL service range from 128 Kbps to 3 Mbps.

DSL Internet services are used primarily in homes and small businesses. DSL Internet service only works over a limited physical distance and remains unavailable in many areas where the local telephone infrastructure does not support DSL technology.