How do you display a page of all the categories and/or tags currently in the Q&A system?

How do you display a page that shows just the categories and/or tags currently in the Q&A system? Right now if I want to find all questions with a certain tag, I have to search the list of all questions looking for one with that tag, and then click that tag. It would be easier if there's a page that lists all the tags in alphabetical order. Same for categories. Is this possible?