This is the first module that I configure when setting up a new drupal site. By default, Drupal passes arguments through the URL, resulting in urls that are difficult to read or remember like http://www.example.com/?q=node/25. Enabling clean URLs removes the dynamic query string "?q=" using mod_rewrite in the htaccess file, resulting in the following, http://www.example.com/node/25. In the past, search engine spiders found it difficult to crawl dynamically generated pages. This is no longer the case. However, the ability to use clean URLs will allow you to use your categories and targeted keywords in your directory and file names which is considered a factor for on site optimization. Embedding your keywords in your URLs serves two purposes. 1.) It enforces an internal website architecture that is centered around tightly structured themes, and 2.) when you have back links you your pages, the keyword enriched URL will sometimes be the anchor text, a key factor in offsite optimization.

The Clean URLs module only works on Apache servers that have mod_rewrite enabled. To configure this, navigate to Administer>Site Configuration>Clean URLs. First click on the "Run Clean URL Test" link. This checks to make sure your server is configured correctly. If so, then you will be able to select Enabled.

If you are on an Apache server but do not pass the clean URL test and do not have direct access to the server configuration, there are a couple tricks you can do to override this. You should uncomment '#RewriteBase /drupal' in the .htaccess file and remove 'drupal'. It should look like this:

Next add the following code snippet to your settings.php file located at site/default/settings.php.

For servers other than Apache, you can find instructions to configure it at http://drupal.org/node/15365.

 

Clean URLs for Drupal 6
If you are using Drupal 6, the option to enable clean urls is automatically turned on by default during the installation process. I have not yet encountered the problem mentioned above where the server does not pass the clean url test running Drupal 6, so I have not tested the workaround for this version.