seme and uke

When I look at yaoi stories I always see the terms seme and uke back in the comments, I guess it's a definition for the top and bottom, but I am not sure. Can somebody explain the term?
2021-05-27 23:23 marked

Introvert hoe's Favorite Tags

What can a Favorite do?

When you find a content posted by another user as interesting, you can click on the "♥Like" button to save it. You can easily find these saved contents in your Favorites list.