nostr is not only a social media like twitter, it is pretty powerful technical stack referred to as "protocol". The essential thing I personally like - your account (identity) is not bound to some one central server (instance of mastodon or twitter itself) - there are "relays" run by different people/organizations, and can be easily run by you as well. It makes nostr pretty nice thing when it comes to censorship resistance, as there is no single point of failure (and there is no "nostr CEO")