When NSFNET and APRANET were interconnected, formed collection of networks, used to connect all the networks of world so called Internet.

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

When NFSNET and the APRANET interconnected, the growth became exponential. Many regional networks joined up, and connections were made to networks in Canada, Europe, And the Pacific.

Sometimes in the mid-1980s, people began viewing the collection of networks as an internet and later as INTERNET, although there was no official dedication with some politician breaking a bottle of champagne over a fuzz ball.

Growth continued exponentially, and by 1990s the internet had grown to 3000 networks and 200,000 computers. In the 1992, the millionth host was attached. By 1995, there were multiple backbones, hundreds of mid-level (i.e, regional) networks, ten of thousands of LANs millions of hosts, and tens of millions of users. The size doubles approximately every year(paxon,1994).

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 now widely used in Eastern Europe, and many others. Numerous transatlantic links are n 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. TCP/IP makes universal service possible and can be compared to the telephone system or the adoption of standard gauge by the railroads in the 19^th century.

What does it actually means to be on the Internet? Our definition is that 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 (email) is not enough, since email is gateway 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 packages to other Internet hosts. It makes since to regard such machines as being on the internet as long as they are connected to the service provider’s router.

With exponential growth, the old informal way of running the internet to 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.

Internet has four main applications:

Email – The ability to compose, send and receive electronic mail has been around since the early days of the APRANET 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 outdistancing the telephone and snail mail.Email programs are available on virtually every kind of computer these days.

News –Newsgroups are specialized forums in which users with a common interest can exchange messages. Thousands of newsgroups exist, on technical and nontechnical topics, including computers, since, recreation, and politics. Each newsgroup has its own etiquette, style, and customs, and woe be to anyone violating them.

Remote login –Using the Telnet, Rlogin, 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, database, and other information are available this way.