What is app instance in firebase project? Is it app by unique users or an app?

Question

I'm creating an android application using firebase cloud messaging. I'm using the concept of the topic of it. I have read the firebase developer page to know about how many topics an app can create and I read the page below link

[Firebase link][1]

My question is what is 'app instance' meant by this line

One app instance can be subscribed to no more than 2000 topics.

And why I'm asking this is, Can I create more than 2000 topics for a project?

and what I got from this is, a user cannot subscribe more than 2000 topics.

please provide a good explanation.

[I have referred this][2]

[And this too][3]

But I can't understand

[1] https://firebase.google.com/docs/cloud-messaging/android/topic-messaging

[2] How many topics can we make in Firebase Cloud Messaging?

[3] How many topics an app instance can subscribe in FCM?

Answer 1

Topics are not really "created" in FCM. You can use as many as you want. All you have to do is refer to them by the unique strings you assign them.

A single app installation may not subscribe to more than 2000 topics.