Cacher is the code snippet organizer for pro developers

<div class="hover_effect">
   <img src="PATH-TO-FIRST-IMAGE" class="first">
   <img src="PATH-TO-SECOND-IMAGE" class="second>
</div>

<style type="text/css" media="screen">
	.hover_effect .second {
   display: none;
}

.hover_effect:hover .first {
   display: none;
}

.hover_effect:hover .second {
   display: block;
}
</style>