Which technology does ADSL refer to?

ADSL stands for Asymmetric Digital Subscriber Line, which is a technology used for transmitting digital data over existing telephone lines. The term "asymmetric" highlights that the data transmission speed is different for upstream (data sent from the user to the internet) and downstream (data sent from the internet to the user) directions. Typically, ADSL provides a much higher speed for downloads than uploads, which is suited for typical internet browsing behavior where users download more data than they upload.

This technology makes it possible to simultaneously use the internet and telephone services over the same line without interference, making it a popular choice for residential broadband connections in many regions.

The other options provided do not accurately represent ADSL. "Automatic Digital Signal Line" and "Adaptive Digital Subscriber Line" are not recognized terms in telecommunications, while "Asynchronous Digital Subscriber Line" misrepresents the foundational concept of ADSL, particularly in the context of internet performance characteristics. Thus, the correct understanding of ADSL clearly aligns with the definition of Asymmetric Digital Subscriber Line.