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The Internet

In the 1950s, just as they are today, computers were used by the military to process the large amounts of information needed for defence. In fact, in the 1950s, computers were so large and expensive that only government organisations and universities could afford to keep computers.

ARPANet	America's Defense Department had a network of computers governed by the Advanced Research Projects Agency (ARPA). A network was better than one big computer that had all the United States' military information on it - just in case that computer broke down or was destroyed. Eventually the ARPANet had tens of thousands of computers attached - with the network spread over a wide area.
JANet	In the United Kingdom most of the computers owned by universities, polytechnics and colleges were linked together to form the Joint Academic Network. This enabled students and researchers to communicate with each other and share information.
Internet	These large networks, and many others, in different countries and on different continents had links between each other. This, in effect, made one huge network of all the other wide area networks: the Internet. Up until the early 1990s using the internet was more complicated than it is today. You had to type commands into your computer to carry out the simplest functions. Then, over the 1980s and 1990s, Tim Berners-Leestarted off the idea of the world-wide web. Along with unique web addresses (URLs), HTTP and HTML (and this meant web sites and web pages).

Protocols

The Internet already had a protocol,TCP/IP, which enabled all the different types of computer to communicate with each other over different operating systems and different languages without getting confused. However, the world-wide web needed another protocol in order to make it work: the HyperText Transfer Protocol or HTTP. It was defined (by Tim Berners-Lee) as a simple way to transfer data over the internet in as quick a time as possible. HTTP is the main method for transferring the HTML for a web page from the server to the browser on the user's computer.

Domain Names

If you type, http://www.ewart.org.uk, into your favourite browser then, hopefully, you will reach this web site. The text that you type in is sometimes called an address, a URL, or a Domain Name. The Domain Name System (or DNS) works like this. The http:// bit refers to the way in which the web-page HTML should be transferred to your computer. The www bit refers to the world wide web, and the ewart part is the unique part of the domain. The abbreviation parts of the domain indicate what sort of site it belongs to. So org is a private organisation (co for commercial; ac for academic; etc.) and uk stands for United Kingdom (au Australia; fr for France; etc.). Domain names have to be registered and they are stored on large databases on the internet (Domain Name Servers). These computers translate the domain names into the IP Addresses that refer to the actual computers that hold the HTML for the web site.

IP Addresses

Each node on the internet has an individual, unique Internet Number, or IP Address. The number is often shown as four numbers (called octets) joined together by full stops ('.').

If you want to put files (such as web pages) on the internet then you also need access to a special piece of software called a server (often this software is on a special computer that only hosts web pages and other files ... in this case both the software and the hardware can be referred to as the server).

World Wide Web

What Tim Berners-Lee did was to push for the development of the Internet so that people could share information, pictures, sounds, etc. by giving each file on the internet a Universal Resource Locator or URL. For example, I have written some HTML code which forms the home page of this web-site (if you want to find it, its URL is http://www.ewart.org.uk/index.html but, of course you knew that already). So, how does it work? How does an HTML file called index.html that I wrote on my computer somewhere in rural Wales appear on your computer in the glory that is the home page of this site?

Just Browsing

If you want to put a web page onto the internet then you have to make sure that it is saved onto a computer that has an IP Address, an internet connection and is switched on and connected all the time. Many companies will allow you to copy your web page onto their computers (which are connected all the time) in return for a fee or advertising. These companies are known as Internet Service Providers or ISPs. They will assign a URL to your HTML file.
Now, if someone knows the URL (or 'address') to your file they can make a temporary copy of the file on their own computer and then look at the HTML code for your site.
However, it is much more interesting to look at the HTML code through a special piece of software called a browser. This software arranges the text and pictures on the computer screen in the places and colours specified by the HTML commands.

Normally, people don't write HTML as straight commands, they use a special editor (such as Macromedia's Dreamweaver, or Microsoft's FrontPage) to create the HTML code for them.