category -> subcategory ->subsubcategory system

[eluser]kmunky[/eluser]
hi there!
first of all i have to mention that i'm quite new to CI. So...i was wondering how can i programatically do a dynamic hierarchical system? you know what i mean.. my url should look something like

Code:

http://mysite.com/category/subcategory/subsubcategory/etc..

and the user can add more and more categories and subcategories to expand the tree.
hope you can help me. thanks :-)