Accessibility and Website Information Skip Site Wide Navigation Skip to Content
Link to the City of San Diego Website Home

The Internet

What Is the Internet?

Several Definitions of the Internet

Internet (upper case "I")

The vast collection of inter-connected networks that are connected using the TCP/IP protocols and that evolved from the ARPANET of the late 60's and early 70's. The Internet connects tens of thousands of independent networks into a vast global internet and is probably the largest Wide-Area Network (WAN) in the world.

The most important technological innovation of our generation, the Internet is actually a network of networks. Originally designed by the U.S. Department of Defense so that a communication signal could withstand nuclear war and serve military institutions worldwide, the Internet was first known as the ARPANet, the most robust communication technology. It is a system of linked computer networks, international in scope, that facilitates data transfer and communication services, such as remote login, file transfer (FTP), electronic mail (e-mail), newsgroups, and the World Wide Web. The Internet greatly extends the reach of each connected computer network (see: network effect, IP).

internet (lower case "i")

When you see "internet" written with a lowercase "i," it usually refers to a group of local area networks (LANs) that have been connected by means of a common communications protocol. Many internets exist besides the Internet, including many TCP/IP-based networks that are not linked to the Internet (the Defense Data Network is a case in point).

How does the Internet Actually Work?

HowStuffWorks - This is a really good site to visit if you want to know much more about how the Internet actually works.

An Atlas of Cyberspaces - This site is for you if you like maps and want a very in-depth treatment of how the Internet works. Not for the faint-hearted!

Internet 101

Copyrighted © 2002-2014 City of San Diego. All rights reserved.