What is Nostr, and why do Bitcoiners use it?

Nostr is a social network that no company owns. Your account is a key you control, so no one can ban you from the whole network, and people can tip your posts in sats over Lightning ("zaps").

Posts go to many independent servers called relays, and you can use any Nostr app, like Damus or Primal, with the same account. Guard your Nostr private key (it starts with "nsec") the way you'd guard a seed phrase. Lose it and you lose the account.