What does ADSL stand for?ADSL = Asymmetric Digital Subscriber Line. It's a line that transmits data - but aysmmetrically, or unequally. The download lane needs more capacity than the upload lane. So, what is ADSL? ADSL is a type of internet connection. It transmits data through existing copper phone lines and it’s the most basic form of broadband. There are three versions – ADSL (ADSL1), ADSL2 and ADSL2+. Each one provides a faster and better internet connection than the last. If ADSL is available where you live, there will only be one version to choose from. You can use ADSL at the same time as your home phone line.