A couple of the feature videos seem to have disappeared in the last year. This one is okay.

Basic idea is choosing whom you share content with, and curating/filtering who's content you see.

Wicked cool to use, but I can't even conceive of how it would work on Nostr/clients.

Communities is a step in the right direction though.
https://youtu.be/GUywKEtXX2c?si=cDWy0YXvRFV7VekK