A:link
This is used to modify the style for normal unvisited links.

A:link
{
text-decoration: overline;
}

A:visited
This is used to modify the style for visited links.

A:visited
{
text-decoration: underline;
}

A:hover
This is used to modify the style for hovered links. The link becomes hovered when the mouse moves over the link.

A:hover
{
text-decoration: none;
color: green;
}