Using push notifications is a great way to add real-time messaging to your application. It allows you to stay in touch with your users and makes it possible for your users to communicate with each other.
Imagine, you are looking for a job. You go to software company daily and ask sir “is there any job for me” and they keep on saying no. Your time and money is wasted on each trip. (Pull Request mechanism)
So, one day owner says, if there is any suitable job for you, I will let you know. In this mechanism, your time and money is not wasted. (Push Mechanism)