Opacity property is used to give some effects on mouseover and out . <html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>Opacity Uses</title>
<style type="text/css" >
img
{
opacity:1.0;
filter:alpha(opacity=100);
}
img:hover
{
opacity:0.4;
filter:alpha(opacity=40);
}
</style>
</head>
<body>
<form id="form1" runat="server">
<div>
<img src="images/1.jpg" />
</div>
</form>
</body>
</html>