How to Set up Page Categories

I have a blog that is set up like a website but in order to do that I have use pages, but the problem I am having is that pages don’t have a category feature like posts have. Having pages categorized will make it easier for me to keep track and update the pages that need it.

So my question is what code do I need to install that will help me add categories to the site as well as where do I need to place the code to make this thing work? Also I know there are plug ins out that that can do this for me but plug ins sometimes aren’t maintained and can cause problems down the road. I have like 100 pages so far and I plan on adding more.