Stands for “Digital Subscriber Line.” It is medium for transferring data over regular phone lines and can be used to connect to the Internet. A DSL circuit is much faster than a regular phone connection, even though the wires it uses are copper like a typical phone line. This is because it transmits and receives data packets in a digital format.
Its a technology that significantly increases the digital capacity of ordinary telephone lines (the local loops) into the home or office. DSL speeds are based on the distance between the customer and telco central office. There are two main categories. Asymmetric DSL (ADSL) is used for Internet access, where fast downstream is required, but slow upstream is acceptable. Symmetric DSL (SDSL, HDSL, etc.) is designed for connections that require high speed in both directions.