When the submit button is pressed on a form, all input tags and their values are sent as parameters to the
servlet or
JSP specified in the action attribute of the form. You can add any number of hidden input fields (using the html:hidden tag) to your form to pass whatever parameters you wish. If you need to change these values"on the fly" as the submit button is being pressed, you can specify a javaScript function in the onsubmit event of the form to modify them.