DSL stands for Digital Subscriber Line. In the simplest terms it is a copper cable like a telephone cable that provides access to a computer network, usually the Internet. The major factor that determines availability is the presence of switches that handle DSL lines at the local phone company s switching office. Distance in terms of feet of cable from the switch at the telephone company office determines the ultimate speed of the connection, much like the quality of the telephone line determines how fast a 56K modem connects. If the distance is too great, DSL will not be available, and the longer the distance the slower the connection.
Most providers can do an approximate distance trace from the switch using a telephone number.
There are many types or flavors of DSL available. It is important to know which type is marketed locally when evaluating the benefits of a DSL connection. Two major considerations for DSL are the upstream and downstream speeds. The different types of DSL connections all have different speeds. Some types are symmetric, both upstream and downstream speeds are the same, and some asymmetric with the downstream being faster than the upstream in most cases.