Internet is a network of networks. How did it come into existence ? How does it function ?

The seeds of today's Internet were planted in 1969, when U.S. Department of Defense sponsored a project named ARPANET (Advanced Research Projects Agency NETwork). The goal of this project was to connect computers at different universities and U.S. defense. Soon the engineers, scientists, students and researchers, who were part of this system, began exchanging data and messages on it. The use­rs of this system were also able to play long distance games and socialize with people who shared their interests. ARPANET started with a handful of computers but it expanded rapidly.

In mid 80's, another federal agency, the National Science Foundation, created a new, high-capacity network called NSFnet, which was more capable than ARPANET. NSFnet allowed only the academic research on its network and not any kind of private business­ on it. So many private companies built their own networks, which were later interconnected along with ARPANET and NSFnet to form Internet.

It was the Inter networking i.e., the linking of these two and some other networks that was named Internet. The original ARPANET was shut down in 1990, and the government funding for NSF discontinued in 1995. But the commercial Internet services came into picture, which are running the Internet.

The Internet is a world-wide network of computer networks. In Internet, most computers are not connected directly to the Internet. Rather they are connected to smaller networks, which in turn are connected through gateways to the Internet backbone.

The Internet functions in the following way:

1. At the source computer, the message or the file/document to be sent to another computer is firstly divided into very small parts called packets. A packet generally contains some information.
2. Each packet is given a number serialwise e.g., 1, 2, 3.
3. All these packets are then sent to the address of destination computer.
4. The destination computer receives the packets in random manner. If a packet is garbled or lost, it is demanded again.
5. The packets are reassembled in the order of their number and the original message/file/document is obtained.