Today Internet is a global web of nearly one million computer networks. Internet host computers are connected to the Internet round the clock.
Brief History of Internet
The Internet was started in 1969 by the defense department of USA. Later, it was handed over to the Defense Advanced Research Projects Agency (DARPA). The DARPA launched the first Internet program. The DARPA established a network of 4 computers and named as ARPANet. The protocols (Software) that define the rules to exchange information between computers were created by DARPA.
The idea of computer networking soon became popular. Several universities & research organizations developed their own computer networks. They joined their networks to ARPANet. The ARPANet became the network of networks. This network of computer networks was named as Internet.
In 1986 the National Science Foundation (NSF), another federal agency of USA, established a network and named as NSFNet. It was established for academic purpose and was accessible to everyone. Later, it was expanded all over the country and large number of universities and research centers were connected to this network. The academic networks were established and all these were interconnected together to share the information. The way of connecting one network to another is termed as internetworking and “Internet” is also derived from internetworking. The NSF provided the connections for academic research centers only. After this many telecommunication companies established their own network backbones by using the same networking protocol as NSFNet used and also provided connections to private users. In 1995, NSF terminated its network on the Internet. Today, the Internet consists of many local, regional, national and international networks.
Network Backbone
The inner structure of the Internet works much like a transportation system. The main communication lines carry the heaviest amount of traffic on the Internet. These communication lines are referred to as Internet backbone. It can also be defined as:
The central structure or element of the network, which connects other elements of the network and handles the major traffic, is called the backbone. The backbone is a high-speed element. It is the major communication link that ties Internet servers across wide geographical areas.
How the Internet works?
It must be noted that there is no particular organization that controls the Internet. Different networks of private companies, government agencies, research organizations, universities etc. are interconnected together. You can say that the Internet is a huge collection of millions of computers, all linked together on a computer network. The network allows all of the computers to communicate with one another. A home computer may be linked to the Internet using a phone-line modem, DSL or cable modem that communicates to an Internet Service Provider (ISP). A computer in a business or university will usually have a network interface card (NIC) that directly connects it to a Local Area Network (LAN) inside the business. The business can then connect its LAN to an ISP using a high-speed phone line such as Ti Line. A Ti Line can handle approximately 1.5 million bits per second, while a normal phone line using a modem can typically handle 30,000 to 50,000 bits per second.
What is ISP?
ISP: It is a company that provides the Internet connections to the users. There are many ISP companies in each big city of each country of the world. You have to get an Internet connection from any ISP company of your local city to connect to the Internet.
ISPs then connect to larger ISPs, and the largest ISPs maintain fiber-optic “backbones’ for an entire region. Backbones around the world are connected through fiber-optic lines, under Sea cables or satellite links. In this way, every computer on the Internet is connected to every -other computer on the Internet. The figure is shown below that shows how an Internet works.
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