Java Server Faces (JSF) tutorials and examples.
When a link or button is clicked by a user, values present in a field get changed or a selection is made in list so that the application might react. Interface components of JSF User would signal certain user action when an event is fired that is being handled by the code.
Event listeners that are very commonly used are value change and action. Others like phase or data model would not be discussed over here. In separate listener or managed bean, it is possible to declare the listeners.