High-speed dedicated digital circuit from a given location to the telephone company's central office, using normal copper telephone lines. DSL is a general term that includes several variations: ADSL (Asymmetric Digital Subscriber Line), HDSL (High-bit-rate Digital Subscriber Line), SDSL (Single-line Digital Subscriber Line), VDSL (Very high-data-rate Digital Subscriber Line) and RDSL (Rate Adaptive Digital Subscriber Line.