For example, when someone opens up:
http://yourdomain.com/something
the actual content that will be displayed can be the one under:
http://yourdomain.com/something/else
although the URL in the visitor's address bar will still remain http://yourdomain.com/something.
You can achieve this by adding rules similar to the ones below into your website's .htaccess file:
| RewriteEngine On RewriteRule ^something/?$ /something/else/ |
Make sure to substitute something and else which the actual directories that you are using on your website.