This link goes to an area of the WordPress Codex that talks about Permalinks, and how to set the different types within WordPress. Permalinks are the links that go directly to a specific article page, and they can be set to many different styles. (if you look at this site you’ll see that my links end in the year, then name of the article) Many major SEO experts like to believe that making your links more human friendly (/my_article_name as opposed to /?p=17) can make a difference in how well your site ranks in search engines. Personally I don’t really see this that much, and most search engines now work perfectly with the default set up in WordPress, but if you’re interested this page explains the way to set things up.
If you were interested in using my structure it’s done by placing the following in the “custom” box in the Options Permalink area: /%year%/%postname%/
Make sure you follow the Codex instructions on how to do your .htaccess file, if not then nothing will work right.