A DSL connection is an Internet connection through 2-wire copper lines and is through the phone's telephone line, states the Xfinity website. DSL stands for digital subscriber line.
DSL Internet connections are connected through the home phone line, but because there are two copper wires, users are able to use the Internet and the home phone at the same time, notes the Xfinity website. DSL connections are typically faster than dial-up connections, which also utilize the home's phone line to connect to the internet. In order to utilize a DSL connection, computers need to be equipped with an internal modem, or users need to purchase or rent an external modem if the computer is not equipped with one.