What is Redis Pub/Sub and how does it work with Node.js?

Redis Pub/Sub (Publish/Subscribe) is a messaging pattern where senders of messages (publishers) do not send messages directly to specific receivers (subscribers). Instead, publishers categorize messages into channels, without knowledge of which subscribers exist. Likewise, subscribers express interest in one or more channels and receive all messages that are published to those channels, without knowledge of any publishers. In Node.js, you can leverage Redis Pub/Sub by using libraries like 'redis' or 'ioredis' to connect to a Redis server, subscribe to channels, and publish messages to those channels.