What's This 'Internet' I Keep Hearing About? - Part Nine - The World Wide Web

I've explained how the Internet works, but not yet how the web works. The web is the publishing system that most people don't realise is distinguishable from the Internet itself.

The Internet uses IP addresses (often found via domain names) to identify resources, but the web has to have something more sophisticated as it would be silly if every single page on the Internet had to have it's own 'domain name'. The web uses 'URLs' (uniform resource locators), and I'm sure you know about these as nowadays they are printed all over the place in the real world.

A typical URL looks like this: :///

For example: http://www.ocportal.com/index.php

HTTP is the core protocol for the web. This is why URLs usually start 'http://'.

Typically the 'resource identifier' is simply a file on the server computer. For example, 'mywebsite/index.html' would be a file on the server computer of the same path, stored underneath a special directory.

We now have three kinds of 'Internet Address', in order of increasing sophistication:

• IP addresses
• Domain names
• URLs

If a URL were put into web browser software by a prospective reader then the web browser would send out an appropriate request (usually, with the HTTP protocol being appropriate) to the server computer identified by the URL. The server computer would then respond and typically the web browser would end up with a file. The web browser would then interpret the file for display, much like any software running on a computer would interpret the files it understands.

An 'HTML' file is the kind of file that defines a web page. It's written in plain text, and basically mixes information showing show to display a document along with the document itself.

I've explained how typical web pages are just files on the disk of a server computer. Increasingly, things are slightly less direct. When you visit something like eBay you aren't just reading files. You're actually interacting with computer software, and the web pages you receive are generated anew by that software every time a request is made. These kinds of systems are known as 'web applications' and are becoming increasingly prevalent.