Counting users in Firebase

Question

I have a very basic and truly new user question about Firebase: Why do I see fewer users in the Database than in the Events analytics? Shouldn't these be the same? Thanks

Answer 1

They will almost certainly never be the same.

Users logged in with Firebase Authentication may be logged in using a single account, from any number of devices, but each one of those devices registers a separate user for the purpose of analytics. This is because analytics doesn't collect any personally identifying information (which is exactly what Firebase Authentication does). Analytics has its own way of identifying a user and their usage of your app.

Also, if your app is uninstalled, then installed again on the same device, it will become another new "user" in analytics, because all the prior context about that device is gone.

See also this question: How does Firebase Analytics define a "user" (for purposes of Audience)?