What does subscription call back URL mean?

A subscription callback URL is the client endpoint that will be invoked using only POST method for qualifying events of the subscribed events.

Our subscription model helps developers reduce overhead for polling for real-time user data by providing notifications whenever the user data is updated. This helps developers in concentrating on using the data rather than finding a way to get the latest data. The subscription model is a push model where the notifications are pushed to the subscribers based on their subscriptions.

You can find more details on our Subscription page.