I want to optimize a series of web pages with mod-rewrite. The pages will be written with this form. example.com/files/1234-keyword1-keyword2/ I know that having keywords in the URL helps, but I want to know if having a number like 1234 might hurt the ranking. The number (like 1234) will passed in the mod-rewrite as a parameter to load the page content. I try to write the URL SEO and user friendly.