The hover event provides a convenient way to trigger behaviours when the user's mouse enters or leaves an element.
The event object passed to handlers has a hover property which is true on mouseenter, false on mouseleave. (The mouseenter and mouseleave events are proprietary Internet Explorer events, which behave slightly differently to mouseover and mouseout. This plugin simulates those events in other browsers. See Quirksmode for more info.)
Be aware that heavy use of hover interactions is generally considered an anti-pattern, since it excludes mobile and tablet users.