In programming, events are occurrences that you can clearly define. An event may be as simple as a mouse click or as complex as the initialization of variables before a report program begins to generate a new user-defined group. Events may reflect major milestones in a project, or they may be any of the countless tiny actions leading to that point.
An event handler, then, is a section of code that provide a response to a specific occurrence. If you have ever clicked a link in a Web browser, you have seen an event handler in action. The event was the click of your mouse button; an event handler then told the browser to load a specified page and possibly to start a new browser window.
Related tasks
Creating an EGL report handler
Related reference
Predefined EGL report handler functions