Event handler that gets attached to a jQuery object thats targeting an element… i.e.

$(h4).click();

The above triggers when you click on a h4 tag, but to get it to actually do something, you need to add a function… i.e.

.click(function({ //do something }));

Or a full example…

$(h4).click(function(){
    $(this).css("background", "#000000");
});