This is adorable link dbasnett.

Its classical. I got so many things from this, but would you please guide me for one thing. It is written there that:
An event sender pushes a notification that an event has happened, and an event receiver receives that notification and defines a response to it.
Where the sender sends the notification? and from where the receiver receives the notification?
I mean that is it some type of checking/ matching procedure behind it? if yes? there where it is matched or checked?