What are subscriptions and unsubscriptions in React?

Question

React

I watch a training video lesson and there the teacher says this sentence:

For example, you subscribed to DidMount, the component works, it works, and then you want the component to close so that you can unsubscribe. If I don’t unsubscribe, there will be a lot of subscriptions and garbage will be collected.

What is a subscription? Who is signing up for what? And why?

If you know an article where you can read about it, please reset it.

Answer 1

event listeners