Asymmetric Digital Subscriber Line
ADSL a communications technology used for connecting to the Internet. Asymmetric DSL is the most common type of DSL connection, especially in homes.
ADSL provides for faster data transmission over copper telephone lines than is possible with a dial-up modem, by using different frequencies. A special filter is installed on the telephone line, allowing both ADSL and regular voice services to use the line simultaneously, without interfering with one another. (Source: Wikipedia)
Unless you know your question is ADSL-specific, you might want to use the more popular dsl tag.
