A URL without parameters is considered to be static, since there will always only be one version of this URL. In contrast, a dynamic URL uses one or more URL parameters in its construction.
Static URL - Dynamic URL
http://www.example.com/8-reasons-why-pizza-is-awesome - http://www.example.com/article?id=234982&ref=ppc&lang=en
Static URLs are typically more friendly to both users and search engines. They're easier for humans to read, type, and remember. For search engines, they can help avoid potential duplicate content issues from using URL parameters. Therefore, static URLs are generally recommended as a best practice, but if done correctly, using dynamic URLs will not hurt the SEO of your site.