We can create a tool tip using CSS. When mouse over the link the tool tip content will display otherwise display none.
a:hover {
background:#ffffff; /*BG color is a must for IE6*/
text-decoration:none;
}
a.tooltip span {
display:none;
padding:2px 3px;
margin-left:8px;
width:130px;
}
a.tooltip:hover span{
display:inline;
position:absolute;
background:#ffffff;
border:1px solid #cccccc;
color:#6c6c6c;
}
<a href="#" class="tooltip">Tooltip<span> Extra info </span></a>