URL Rewriting
By default, TYPO3 urls are of the form www.thedemo.ca/index.php?id=34 (some number). There are several url rewriting options available however to change that to something more friendly.
This site uses RealURL, and if you notice, the url of this page is www.thedemo.ca/extension-module-demonstrations/url-rewriting.html. It's a friendly, more "real" url, in terms of thinking about where a visitor is on the website.
The actual form it takes is configurable, though there are some helper extensions, like cbrealurl to help set up the urls for many TYPO3 functions. It's possible to specify the terms that appear in the url, or leave them completely auto-generated.
There are other url rewriting extensions available, such as simulate static and cooluri, they have different configurations and slightly different options, but the end result is to give a website friendlier urls.

