Wikipedia
Internet service provider
An Internet service provider (ISP), also sometimes referred to as an Internet access provider (IAP), is a company that offers its customers access to the Internet. The ISP connects to its customers using a data transmission technology appropriate for delivering Internet Protocol datagrams, such as dial-up, DSL, cable modem, wireless or dedicated high-speed interconnects.
ISPs may provide Internet e-mail accounts to users which allow them to communicate with one another by sending and receiving electronic messages through their ISPs servers. (As part of their e-mail service, ISPs usually offer the user an e-mail client software package, developed either internally or through an outside contract arrangement.) ISPs may provide other services such as remotely storing data files on behalf of their customers, as well as other services unique to each particular ISP.
End-user-to-ISP connection
ISPs employ a range of technologies to enable consumers to connect to their network.
For users and small businesses, the most popular options include dial-up, DSL (typically Asymmetric Digital Subscriber Line, ADSL), broadband wireless, cable modem, fiber to the premises (FTTH), and Integrated Services Digital Network (ISDN) (typically basic rate interface).
For customers with more demanding requirements, such as medium-to-large businesses, or other ISPs, DSL (often SHDSL or ADSL), Ethernet, Metro Ethernet, Gigabit Ethernet, Frame Relay, ISDN (BRI or PRI), ATM, satellite Internet access and synchronous optical networking (SONET) are more likely to be used.
; Typical home user connection
* Dial-up
* DSL
* Broadband wireless access
* Cable Internet
* FTTH
* ISDN
* Wi-Fi
; Typical business-type connection
* DSL
* SHDSL
* Ethernet technologies
Locality
When using a dial-up or ISDN connection method, the ISP cannot determine the callers physical location to more detail than using the number transmitted usi read more at » http://en.wikipedia.org/wiki/Internet+service+provider