Hi,
The linked documentation provides examples and explanations for
event handling.
Just as an example,
OnBeforeCommentSaved allows you to interrupt the default process and run custom code before the comment is saved. Lets say you wanted to convert the text to all caps - once the user presses save you call this event which specifies that your conversion method should be ran before the text is saved.
Please review the documentation and let us know if you have any additional questions.
Thanks,
Sandro