What "e" represents here?

What "e" represents here?

Hi 

In the following code : 

$("body .ribbon-container li")
            .delegate("a", "hover", function ( e) {
                "mouseenter" == e.type && showSecondryImages($(this), e.type), "mouseleave" == e.type && showPrimaryImages($(this), e.type)

What " e " represents in this code ?

Waiting for your response!!!!!!!

Thanks 
Varun