With nostr, you choose a client (app or website), and post a note. Anyone using any nostr client can see your note, because the note is not stored on centralized servers. It is stored on relays that anyone, including you, can build on a computer.

You have a private key that authorizes notes, and a public key that everyone else sees. When you follow someone, you follow their public key; but this has been abstracted away to simply show display names.

It is a truly a decentralized and censorship resistant protocol 💜