The Internet

The Internet is a worldwide network, of computers.  It got started in late 1960s, originally conceived as a network which could survive nuclear war. Back then it was called as ARPAnet, named after Advanced Research Project Agency (ARPA) of United States federal government.

Protocol and packets
When people began to connect their computers into the ARPAnet, the requirement became clear for a universal set of standards, called as protocol, to ensure that all the

machines speak the same language. The modern Internet is such that you use any type of computer IBM compatible, Mac, or other and take advantage of all network’s resources.

All the Internet activity consists of computers talking to one another. This occurs in the machine language. However, situation is vastly more complicated than when data goes from one place to other within the single computer. In Internet (often called as the Net), data should often go through several different computers to get from transmitting or source computer to receiving or destination computer. These intermediate computers are called as nodes, hosts, servers, or Internet service providers (ISPs). Millions of the people are simultaneously using Net; the most efficient route between the given source and destination can changes every moment. The Net is set up in such a way that the signals always try to follow most efficient route.

If you are connected to a distant computer, such as a machine at the National Hurricane Center, the requests you make of it and data it sends you are broken into small units called as packets. Each packet coming to you has, in effect, your computer’s name on it. But not all the packets necessarily travel the same route through the network. Ultimately, all packets are reassembled into data you want, say, the infrared satellite image of a hurricane, and even though they may not reach in the same order they were sent.

The figure given below is a simplified drawing of the Internet data transfer for a hypothetical file containing 5 packets transferred during the period of extremely heavy usage. Nodes are shown as the black dots surrounded by the circles. In this instance, some packets pass through more nodes, and over a much greater physical distance, than the others. If Net traffic were very less, all the packets may follow the same route through the fewer nodes. This is why it takes longer to acquire the data on Net during the peak hours of usage, as compared with the times when there are comparatively few people connected to it. A file cannot be reconstructed completely until all the packets have arrived and destination computer has verified that there are no errors