What is the best design for subpages and subcategories?

I am developing my own mvc-based framework. I have pages which have their own subpages with links like: domain.com/page/subpage. I have also categories which have their own subcategories with links like: domain.com/category/subcategory.

I do not want to have some links like: domain.com/stack/overflow for both subpages and subcategories, that may be happen in large databases and contents.

How should I handle the parent pages or categories in the links? What is the best design for the subpages and subcategories links?