submit buttons: When activated, a submit button
submits a form. A form may contain more than one submit button.
reset buttons: When activated, a reset button resets
all controls to their initial values.
push buttons: Push buttons have no default behavior.
Each push button may have client-side scripts associated with the
element's event attributes. When an event
occurs (e.g., the user presses the button, releases it, etc.), the associated
script is triggered.