It helps to keep the parameters short and the number of them few. the URL contains a '?' character), be aware that not every search engine spider crawls dynamic pages as well as static pages. Research suggests this may not be as big of a problem for major search engines as it once was however, it is worth noting the recommendation from Google's webmaster guidelines stating: The style of URLs using '?q=' can be hard to read, and may even prevent some search engines from indexing all the pages of your site. With so-called clean URLs this would be displayed without the '?q=' as ' '. For Drupal 8 see troubleshooting-drupal-8/fix-drupal-8-clean-urls-problems
This page contains instructions relating to Drupal 7.
