Calling $( selector ).hover( handlerIn, handlerOut ) is shorthand for:

$( selector ).mouseenter( handlerIn ).mouseleave( handlerOut );

ex:

$( "li" ).hover(
function() {
$( this ).append( $( "<span> ***</span>" ) );
}, function() {
$( this ).find( "span:last" ).remove();
}
);