Drupal's default URL structure is like "http://www.sitename.com/?q=node/10″ This URL format can be hard to read, and can sometimes prevent search engines from indexing all your pages properly. In this case you can eliminate this "?q=" and clean the URLs through the following steps.

Navigate to Administer » Site configuration » Clean URLs. By default, it will be disabled. Select enabled and click the save configuration button. You are done.

You can make your URLs even more cleaner with the help of path module.

Home » Administer » Site building » Modules: enable the Path Module.