DSL or xDSL, is a family of technologies that provide digital data transmission over the wires of a local telephone network. DSL originally stood for digital subscriber loop, although in recent years, many have adopted digital subscriber line as a more marketing-friendly term for the most popular version of consumer-ready DSL, ADSL. Typically, the download speed of consumer DSL services ranges from 256 kilobits per second (kbit/s) to 24,000kbit/s, depending on DSL technology, line conditions and service level implemented. Typically, upload speed is lower than download speed for Asymmetric Digital Subscriber Line (ADSL) and equal to download speed for Symmetric Digital Subscriber Line (SDSL). Source: http://en.wikipedia.org/wiki/DSL

DSL is a type of internet service that uses the phone line coming to your home to also carry internet traffic. It's a similar concept to cable internet. In this case, DSL makes use of the full capabilities of your phone line (only part of which are used by your phone calls). For DSL to work, you need a DSL modem at your home and an available connection to a DSLAM (provided by your internet provider) at the other end of your phone line at the CO (central office). This is what allows your phone line to carry internet traffic and phone calls at the same time. In order to get DSL, you also have to be fairly near (within 3 miles or so) to your neighbourhood CO, where all the phone lines come together and get digitized. If you're too far away from this facility, you won't get satisfactory speeds and the internet provider may not offer the service. This is also why DSL isn't typically available in rural areas, only built up residential areas where the phone system has been upgraded to digital.

DSL, or Digital Subscriber Line, is a type of high speed Internet access. When deciding on which type of Internet access to get, you may have several options: dial up, DSL, cable, fiber optic, satellite, mesh wireless or point distribution wireless. However, in many geographic locations you may be limited in the types of Internet access that are available to you. DSL Internet access is delivered across the telephone network backbone and in most homes in the United States, an ordinary telephone connection jack can be used to plug in to DSL Internet access. Not all phone companies offer DSL service in every residential area, so even if phone service is available, it does not necessarily mean that DSL will also be available.

DSL, or Digital Subscriber Line, is a type of high speed Internet access. When deciding on which type of Internet access to get, you may have several options: dial up, DSL, cable, fiber optic, satellite, mesh wireless or point distribution wireless. However, in many geographic locations you may be limited in the types of Internet access that are available to you. DSL Internet access is delivered across the telephone network backbone and in most homes in the United States, an ordinary telephone connection jack can be used to plug in to DSL Internet access. Not all phone companies offer DSL service in every residential area, so even if phone service is available, it does not necessarily mean that DSL will also be available. You can get DSL service from companies other than your local phone company, however, so even if the phone company doesn't provide DSL service, there may be other local companies who do. Read more about how to choose a DSL provider in your area. As compared to a dialup connection, where a modem is used to connect to the Internet over the phone lines, DSL is always on. There is no need to dial in or disconnect. And DSL is generally much faster than a dialup connection which is limited to 56k.