The URL for your content items is a key factor in your SEO efforts. It's generally agreed among SEO practitioners that keywords in your URL are influential on the way search engines view that content item. Accordingly, you want to make an effort to use the URL as a way to advance your SEO goals.
Drupal's Path module provides you with enhanced ability to create more search engine effective URLs. Assuming you have set your Drupal site to use Clean URLs and that the Path module is active, as described previously, Drupal will automatically create URL aliases for your content items. The automatic aliases, however, are based on the article's title, and may not always be optimal. While the default aliases may be fine for some sites, if you are concerned about competitive SEO you will want to exercise your own control over the aliases. Fortunately, Drupal makes it possible for you to specify your own URL aliases.