The Chinese name of DSL is digital subscriber line, which is a combination of transmission technologies using telephone lines as transmission media. DSL technology supports symmetric and asymmetric transmission modes on the user loop of public telephone network, and solves the "last mile" transmission bottleneck problem that often occurs between network service providers and end users. Because the DSL access scheme does not need to transform the telephone line, it can make full use of the telephone subscriber loop that can be laid in large quantities, greatly reducing the extra expenses. Therefore, the use of copper telephone lines to provide higher-speed Internet access is more popular with users, has attracted the attention of all parties, and has been widely used in some countries and regions.

DSL includes ADSL (Asymmetric Digital Subscriber Line), RADSL, HDSL, VDSL, etc.