Never say never! There are various settings that can change this by site or account, but the defaults are:
- New: a topic that was created within the past 2 days that you haven’t opened yet
- Unread: topics you’ve already read that have new replies
- Unseen: topics you’ve never read at any point (hidden by default, a bit of a niche case)
The hope with the combined new is that the labels topics/replies are a little more intuitive than figuring out the difference between new/unread