About the Internet

A Brief History of the Internet

The Internet is a worldwide publicly accessible interconnected series of computer networks. Sometimes referred to as the network of networks. All the computers are linked by a common protocol or language known as Internet Protocol or (IP). But that was not always true.

The Internet began in the early 1960's as a project of the United States Department of Defense. It's objective was to develop a military Command and Control system that could survive a nuclear war.

In October 1962 J.C.R. Licklider was appointed head of the United States Department of Defense's Defense Advanced Research Projects Agency (DARPA). One project was to interconnect three different computer networks:

The heart of this problem was the connection of computers from different manufacturers in different parts of the country each of which spoke a unique protocol or language. Every computer manufacturer had its own network protocol, so there was no common language between computers from different companies.

At around the same time the RAND Corporation and Leonard Kleinrock at MIT developed a method of Packet Switching to interconnect computer networks the same way that telephone networks interconnected. After all, one could place a telephone call from Pacific Bell to New York Bell or England or France. Not much different than the already solved problem of interconnecting telephone networks.

On October 29, 1969 the first packet of information was sent between two different manufacturers computers. A video of the event is on YouTube HERE.

In the early 1970's the International Telecommunications Union (ITU) in Europe refined packet switching into a commercially available standard known as X25.

Packet Switching or X.25 uses the standard telephone system to send packets of text data from one point to another.

Packet Switching Example

Let's assume a 1,000 character message is to be sent from Berkeley to Boston. At the originating location the message is first broken into small packets by the Transmission Control Program - say 200 characters each. That makes five packets. Now, since the computers are connected through the telephone system each packet is sent as a separate message and each packet may take a different route. For example:

Packet 1 went Berkeley - Chicago - Boston

Packet 2 went Berkeley - Las Vegas - St. Louis - Cleveland - New York - Boston

Packet 3 went Berkeley - Los Angeles - Chicago - Cleveland - Boston

Packet 4 went Berkeley - Seattle - Las Vegas - Tampa - New York - Boston

Packet 5 may go Berkeley - Boston

The packets arrive in this order 5,1,3,4,2. When all are all received, TCP at M.I.T. reassembles the packets into the original message.

In all, various parts of the message have gone through Las Vegas, Seattle, Chicago, Saint Louis, New York, Cleveland and Tampa.

In 1973 Vint Cerf took the different packet switching protocols and produced a non-proprietary public domain protocol to interconnect networks known as Transmission Control Protocol/Internet Protocol (TCP/IP). This was the first known use of the word Internet.

The Internet was designed to send simple messages between computers. What we now know as email.

The National Science Foundation (NSF) started the first National Center for Supercomputing Applications (NCSA) at the University of Illinois in 1985. In 1986 control of the Internet was turned over to the NSF to connect the Supercomputing Centers.

The Internet was different back then. Because it started with the military, there were some computers that belonged to the military, some which belonged to computer companies, some that belonged to government agencies, and some that belonged to educational institutions. To differentiate, the concept of a top-level domain was introduced to identify users.

The original set of Top Level Domains were:

.mil to identify military users like

.com to identify private companies like

.gov to identify government agencies like

.edu to identify educational institutions like

.us to identify private users in specific countries like

.org to identify organizations like

.net to identify other network users like

In the early 1990's two events caused explosive growth of the Internet. First was the invention of hypertext and second was privatization.

A complete list of Internet Country Codes and all the Internet High Level Domain Names may be found at the Internet Assigned Name Authority in the Root Zone Database.


Servers and Clients

There are two types of computers on the Internet: Servers and Clients.

Servers do exactly what the name implies; they serve information to other computers. Client computers are the receivers of that information. When you are on the Internet, your computer is a Client connected to your ISP's Server. You are using client software on your computer - it may be an email program like Outlook Express or a web browser like Internet Explorer.


Web Browser

A web browser is a program the reads hypertext and renders that text on your computer screen. For a complete description please see the Help section on Web Browsers.



When the Internet was under control of the NSF, one of the primary uses was the exchange of physics papers. Information about physics required more than just words. Illustrations, photographs, movies, sound were also required to convey the information. All of which were awkward on the email based 1980's Internet. In 1989, the English scientist Tim Berners-Lee at CERN, the European Physics Agency invented the World Wide Web to encompass these various types of media with hypertext. Hypertext is a method to connect individual documents with hyperlinks. By 1993 the National Center for Supercomputing Applications at The University of Illinois developed the Mosaic Web Browser to display these documents. The same students at the University of Illinois who developed Mosaic, later formed a company called Netscape, then Mozilla ( Firefox).



In 1991 the Internet was privatized. Control was phased from the NSF to the newly formed Internet Society, headed by Vint Cerf. For the first time commercial use was allowed. Internet Service Providers (ISP's) like Mindspring, CompuServe, AOL, TelNet, Earthlink, Prodigy, Zdnet, Telerama and SonNet sprang into existence. Since the method of connection was a telephone line, every telephone company also became an ISP, as it required no additional infrastructure.