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What is the internet?

It has revolutionised our lives with its technical capabilities, but how did the internet originate and how did it manage to spread across the world and reach more than a billion users?

The internet is a global network of computers that works much like the postal system, only at sub-second speeds. Just as the postal service enables people to send one another envelopes containing messages, the internet enables computers to send one another small packets of digital data.

For that to work, they use a common ’language’ called TCP/IP (Transmission Control Protocol/Internet Protocol). If you are on the net, you have an IP address.

How it works

When you send a letter, you don’t need to know about the vans, trains and planes that carry it to its destination, or how many post offices it passes through on the way. Nor do you need to know how your packets of internet data are transmitted through a variety of cables, routers and host computers on the way to their destination.

However, different packets can take different routes, which makes the internet relatively resilient. The failure of a particular node or host generally makes little or no difference to the rest of the system.

When you put an envelope in the post, it can contain many different types of data: a love letter, an invoice, a photograph, and so on. The internet’s data packets also carry different types of data for different applications. Common types include web pages, email messages, and large files that might be digital videos, music files or computer programs.

Today, the web is often used to provide an easy-to-use interface for numerous applications, including email, file transfer, Usenet newsgroups, and messages (Internet Relay Chat). This makes the web and the internet appear to be the same thing. However, these applications existed before the web was invented, and can still run without it.

Origins of the net

The internet traces its origins to the ARPA-net, created by the US Defence Department’s Advanced Research Projects Agency in the 1960s. Many other networks were developed - some by commercial companies, some in different countries - but they couldn’t easily talk to one another. “Vint Cerf” and “Bob Kahn” developed TCP/IP, ’A Protocol for Packet Network Interconnection’ (in 1974), to connect different networks. The internet was thus a ’network of networks’, although the Internet Protocol (IP) came to dominate networking. At the end of 1969, there were only four computers on ARPA-net, and they were all at US universities. This grew to 5,000 internet hosts in 1986, after which the number of users grew rapidly into the millions and then hundreds of millions.

Global domination

The main reasons for this massive increase were the opening of what had been an academic and government network to commercial users, and its rapid spread from the US to the rest of the world.

Allied factors were the huge growth of the personal computer market in the 1980s, the invention of the World Wide Web by Tim Berners-Lee in the early 1990s, and the widespread adoption of broadband in the 2000s.

Web browsers have made the internet easy enough for anyone to use. With relatively cheap personal computers and the benefits of broadband, more than a billion people are using it. Now that internet access is becoming popular on mobile phones, the next billion users should be online fairly soon.