There are two major types of DSL (Digital Subscriber Line). ADSL (asynchronous) and SDSL (synchronous). They are the follow on to ISDN (Integrated Services Dial Network). xDSL lines provide huge bandwidth over standard copper phone lines.

ADSL provides a faster down stream speed than it's up stream speed. Standard downstream speeds in the UK are 512K/1M/2M with a fixed upload speed of 256K. It is specifically geared for home users because it can download much faster than it can upload. SDSL provides the same speed down and up stream. It is geared for businesses that want to run their own mail server, web server, etc. Standard speeds are 512K/1M/2M.

All xDSL lines require a special modem or router.