The Internet

The number of networks, machines, and users connected to the ARPANET grew rapidly after TCP/IP became the only official protocol on Jan 1, 1983.

When NSFNET and the ARPANET were inter-connected, the growth became exponential. Many regional networks joined up, and connections were made to networks in Canada, Europe, and the Pacific. People began viewing the collection of networks as the Internet.

Growth continued exponentially, and by 1990 the Internet had grown to 3000 networks and 200,000 computers. In 1992, the one millionth host was attached. By 1995, there were multiple backbones, hundreds of mid-level (i.e., regional) networks, tens of thousands of LANs, millions of hosts, and tens of millions of users.

The size doubles approximately every year. Much of the growth comes from connecting existing networks to the Internet.

In the past these have included -

• SPAN - NASA 's space physics network
• HEPNET - a high energy physics network
• BITNET - IBM's mainframe network
• EARN - a European academic network widely used in East Europe,
• and many others.

Numerous transatlantic links are in use, running from 64 kbps to 2 Mbps.

The glue that holds the Internet together is the TCP/IP reference model and TCP/IP protocol stack.

What does it actually mean to be on the Internet ?

A machine is on the Internet if it runs the TCP/IP protocol stack, has an IP address, and has the ability to send IP packets to all the other machines on the Internet.

The mere ability to send and receive electronic mail is not enough, since email is gatewayed to many networks outside the Internet. However, the issue is clouded somewhat by the fact that many personal computers have the ability to call up an Internet service provider using a modem, be assigned a temporary IP address, and send IP packets to other Internet hosts. It makes sense to regard such machines as being on the Internet for as long as they are connected to the service provider's router.

With exponential growth, the old informal way of running the Internet no longer works. In January 1992, the Internet Society was set up, to promote the use of the Internet and perhaps eventually take over managing it.

Traditionally, the Internet had four main applications, as follows:

Email: The ability to compose, send, and receive electronic mail has been around since the early days of the ARPANET and is enormously popular. Many people get dozens of messages a day and consider it their primary way of interacting with the outside world, far out-distancing the telephone and snail mail. Email programs are available on virtually every kind of computer these days.

News: News groups are specialized forums in which users with a common interest can exchange messages. Thousands of news-groups exist, on technical and non-technical topics, including computers, science, recreation, and politics.

Remote login: Using the Telnet, RIogin, or other programs, users anywhere on the Internet can log into any other machine on which they have an account.

File transfer: Using the FTP program, it is possible to copy files from one machine on the Internet to another. Vast numbers of articles, databases, and other information are available this way.

Up until the early 1990s, the Internet was largely populated by academic, government, and industrial researchers.

One new application, the WWW (World Wide Web) changed all that and brought millions of new, non-academic users to the net. This application, invented by CERN physicist Tim Berners Lee, did not change any of the underlying facilities but made them easier to use. Together with the Mosaic viewer (browser), written at the National Center for Supercomputer Applications, the WWW made it possible for a site to set up a number of pages of information containing text, pictures, sound, and even video, with embedded links to other pages. By clicking on a link, the user is suddenly transported to the page pointed to by that link.