
</center>

<h2>
	Key concepts
</h2>

<hr/>

<h4 id="event">
	Event
</h4>

<p>
	It is like a thing that has happened. Each event has a type, a subtype and
	it contains information about its emitter and has some optional data that
	can be attached to the event.
</p>

<h4 id="listener">
	Listener
</h4>

<p>
	It allows the event system to keep track of all of the other systems,
	entities and components that are interested in an event.
</p>

<p>
	After a registrant has registered an event listener for a specifi