What are DSL / Digital subscriber line?

What are DSL / Digital subscriber line?
DSL or digital subscriber line is a service that makes the use of existing copper telephone wires for transfer data services at extreme speed. It does not hamper the existing line and also surf the internet with talk on phone, simultaneously.DSl offers speed that around 5 to 30 times higher than a typical 56 kbps dial-up connection. That helps that websites would load quickly, faster downloads, faster videos buffering and the domain of online games would be illimitable.
DSL can be categorized in three divisions. There are given below.
ASDL (Asymmetric digital subscriber line): - It offers download speed of 1.5 Mbps and upload speed of 385k. in order to acquire a ADSL connection. Your location has to be with in 3 miles of your local telephone exchange. DSL router is need for this connection,
IDSL (ISDN digital subscriber line) :- IN IDSL connection distance is not considered. In IDSL ISDN router is required and it provide a connection speed of 144k.
SDSL (Symmetric digital subscriber line) :- The speed available under this type of DSL connection depend upon the distance between location and local telephone exchange.
Advantages of DSL: - no installation of new wires required. DSL uses the present telephone line to connect to the internet. It provides extremely fast connection. The download rate is much faster in DSL. A DSL connection is very secure.
Disadvantage of DSL: - The quality of your DSL connection depends upon the distance between location and your local exchange. DSL provide high speeds for downloading stuff but upload speed are not good.
DSL vs Cable modems: - The service provides through a cable modem can sometimes slow down or gets hanged. It depends on the no of users accessing that particular service. But, in a DSL connection there is no such problem. The speed of DSL is consistent and high. This does not allow any kind of conjunction on the networks. It provides more security than the cable modem connection.