SEO friendly URLs with apache mod_rewrite

I assume that the reader is familiar with the "SEO friendly URLs" concept. If not you can start reading these:

At the cost of beating my own drum, I will consider a real case: It is an image gallery where the contents are organized in a structure like this:


So the smartest way to write the URLs would be: (external URL). The internal URL, actually managed by the cms and more concise, is: As you can see, the external URL is SEO and user friendly. It embeds the id number of the language/category/gallery/photo. In addition, reading the URL gives the user an understanding of the site's topic and organization.