Whenever a new user signs up, a user profile is automatically created for
you to track user information other than their username, email or password. Username, email and password are stored inside the reserved
_user database, but user profile is stored in the public
user database. They share the same column
_id with exactly same value. You can access the
user profile the same way as accessing a record, and everything stored in
user profile is public and thus visible to any user.