Events represent the activity that occurs between the user and the application. 
Java�s Abstract Windowing Toolkit (AWT) communicates these actions to the programs using events. 
When the user interacts with a program, by clicking a command button, the system creates an event representing the action and delegates it to the event-handling code within the program. 
This code determines how to handle the event so the user gets the appropriate response. 
Java provides the Event class and each event is represented by an object that gives information about the event and identifies the event source. Whenever an event occured by an event sourse, 
An appropriate evetnt handler(EventListener) is called. The Event Listener knows that how to handle the handle.