title: How the notification system of any messaging app works
body: <p>I apologize for my English right away. My question is very simple: when I send a message to a person, how does that particular person receive the notification? I know there are many services that do this, but I would like to understand the process behind it. My theory is this: there is a trigger on the message table, as soon as a record is added to this table, the backend sends a notification to the person, but the thing I don't understand is how can I track the person, I don't believe via IP since it is unreliable. I really apologize for my ignorance and I hope you can help me.</p>