nats.docs/nats-concepts/pubsub.md

Publish-Subscribe

NATS implements a publish-subscribe message distribution model for one-to-many communication. A publisher sends a message on a subject and any active subscriber listening on that subject receives the message. Subscribers can also register interest in wildcard subjects that work a bit like a regular expression but only a bit. This one-to-many pattern is sometimes called fan-out.

Try NATS publish subscribe on your own, using a live server by walking through the pub-sub tutorial.