What do you understand by an event? Give example

Answer 1

event is occurance of an activity.
Example, when you click a button.
or mouse click etc.

Answer 2

Events are basically messages that can be "fired" (that's the word). An object that can fire also can attach "listeners". Those are the subscribers for the messages. So an icon might fire "I am the icon X. I was clicked twice with left button." Then another object might open a file or something.