Topics make it easier for content to be discovered. When you tag a topic on a post, it appears in:
The general Discover feed (visible to everyone by default)
The specific Topic feed (for users actively browsing that topic)
You can browse topics by going to the Explore page.
If you don't see a topic you're interested in, let us know — we welcome suggestions: https://support.upscrolled.com/hc/en-us/requests/new
Note: Selecting a topic is only available for public accounts (not private accounts).