Information is exchanged over the Internet in the form of a coding language known as HTML (Hypertext Markup Language). HTML describes the way in which elements will appear on a document published to the Internet, both in terms of physical appearance of the page and text (background colour, text size and colour, italics, bold etc.) and the position of elements on the page (left, right, centred, text wrapped around images, in tables etc.) in much the same way as a word-processing program works. HTML also allows added dynamic effects not offered by traditional text, such as allowing users to complete and send forms and mail messages from web pages, blinking and colour changing of text etc.

Information is represented in the form of tagged instructions which appear either side of the selected text, e.g. text slightly larger than the main body of the text and coloured red would appear as

<font size="+1" color="red"> text</font>

Images are embedded into web pages by using &ltimg7gt tags that identify the image's size in pixels (the smallest measurement of graphic size) and where to find the image on the server. Example HTML for a small square photograph called "me" found on the right side of the page would be

<img src="me.gif" height=50 width=50 align=right alt="photograph of myself">

where the alt= instruction contained the text that will be displayed if the requested image cannot be found. An example of HTML taken from the site appears at the end of this paper, along with an illustration of how the same page appears when viewed through a browser.

The main advantage of HTML is that it supports hypertext through the use of links and anchors, which appear as the &lta> and </a> tags. A hyperlink from page 1 to page 2 in a hypertext document may be

<a href="page2.html">click here to continue</a>.

Similarly, images can be used as anchors to subsequent pages or documents by combining anchor and image information in the HTML coding,

<a href="page2.html"><img src="button.gif"></a>

The hypertext references mentioned above are given in a form known as URLs (Uniform Resource Locators), which are made up of three components

1. the access method by which the user receives the information from the Internet (http= hypertext transfer protocol, ftp= file transfer protocol etc.)
   
   
2. the Internet address of the server which stores the object (e.g. www.host.com)
   
   
3. the address of the document on the server, including the directory in which it is stored and the name of the file (e.g. myfiles/images/me.gif)

A complete URL would be therefore be http://www.host.com/myfiles/images/me.gif.

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