a curated set of notes, like wss://relays.land/spatianostra;

an algorithm that fetches data from other relays and sorts them somehow, like wss://algo.utxo.one;

a relay where people intentionally publish exclusive notes to, like wss://imp.relays.land or wss://topic.relays.land/praise;

a semi-closed community, like wss://pyramid.fiatjaf.com;

a personal utility service, like wss://bookmarks.relays.land or wss://personal.relays.land;

a set of people self-selected according to some filtering criteria, like wss://nostr.wine or wss://nostr.land;

a semi-open public relay with intentional directed posts but strict moderation, like wss://relays.land/bitcoindev;