1.1: What is the Internet?

The Internet is is a huge network of high-speed telephone lines and satellite relays designed to link computers and carry digital information worldwide. Across the globe, governments and private enterprises have laid millions of feet of fiber-optic cables. Using specialized computers called servers, modems and routers, among other equipement, Internet service providers make it possible for us to hook into this network and communicate instantly with other computers — and other people — worldwide.

Types of networks

A distributed network

Paul Baran

Paul Baran

In his pioneering research in the 1960s, Paul Baran envisioned a communications network that would survive a major enemy attacked. His sketch above shows three network topologies described in his RAND Memorandum, “On Distributed Communications: 1. Introduction to Distributed Communications Network” (August 1964). The distributed network structure offered the best survivability because of its superior number of “redundancy levels.” If one path through the network is destroyed, many alternate paths are available.

This redundancy helps speed up the Internet under normal circumstances because data is split up into packets and sent through several paths at the same time.

This short video will explain how this works:

A packet’s journey