Stands for "Internet Service Provider." It's how just about all homes are connected to the Internet. Most ISPs are made up of a network of servers, including Web, e-mail, and news servers). When your modem dials your ISP, a point-to-point protocol (PPP) connection is established with another modem on the ISP's end. From there, you are connected to routers which route you to the Internet "backbone". From there, you can access stuff from anywhere around the world.
ISP
Meaning of ISP in English
English glossary of computer and Internet terms. Английский глоссарий компьютерных и Интернет терминов. 2012