The Internet began as ARPANET, a way for the U. S. Department of Defense to share critical data with its staff and contractors across the United States. As a national defense tool, ARPANET needed the ability to survive attacks, even nuclear attacks, and so it was designed to be geographically distributed, without a central structure and loaded with built-in redundancies and alternative routes. Later, ARPANET merged with a similar network built by the National Science Foundation (NSF) which was devoted to connecting research and educational institutions. Together, they formed the basis for what is now referred to as the Internet.

For many years, traffic on these networks was restricted to Defense Department contractors, researchers and members of higher education institutions. Due to government funding restrictions and use policies, commercial users were not permitted access until about 1990. Then, most of those restrictions were relaxed or eliminated, and individuals and commercial users surged onto the Internet. Today, the Internet is mostly supported by commercial backbones (backbone is a term for a primary supporting structure in a network). Every company, institution, organization and user supports its own piece of the Internet when they add a new network or computer.

The Internet's logical network is composed of millions of smaller Local Area Networks (LANs) that are joined together and share a common method for communicating with each other, called a protocol. The Internet uses a protocol called TCP/IP for sending packets of information back and forth between computers. That's really what makes the Internet work. Through this common protocol, you have the ability to share information globally without worrying about where the information is physically located. Tools for using the Internet can find information no matter where it is, thanks to this common, agreed-upon standard.

For more information about the nature and history of the Internet, see:

Online Information:

• Hobbes' Internet Timeline
• Explore the Internet

Books:

• The Internet Unleashed, 2nd edition
  By Steve Bang, Martin Moore, Rick Gates, et al, Sams Publishing.
• City of Bits: Space, Place, and the Infobahn
  By William J. Mitchell, MIT Press.