Category pages are Instant Answers within a particular category, e.g. The Simpsons Characters. They are often linked to in the Related Topics boxes that appear to the right of Instant Answers. They can also be reached directly through searches.
While viewing a category page, you can click the grid icon at the top right to expand the category entries. Clicking a letter from the list at the top will send you to that letter's section of the category.
Our category pages are actually automatically generated. That is, we do not moderate them directly or manually. Therefore, to add a result to a particular category page, you should work to add it to the underlying source. You can find the source, e.g. Wikipedia, by clicking on a topic on the category page, and then looking for the link in the Instant Answer. If you get the result added there (to that specific source) it should auto-flow to us and everyone else who draws on that information.
Prior versions on GitHub.