In object-oriented languages, objects expose encapsulated functions called methods. Methods are encapsulated functions which run when they are invoked.
Sometimes, however, we think of the process of method invocation more grandly. In such a case, the method invocation is termed an 'event', and the running of the method is the 'handling' of the event. An standard example of an event is a user's selection of a button on a graphical user interface; this action may trigger a number of methods to 'handle' it