The Visited Pseudo-class applies to hyperlinks (in HTML, <A HREF> elements)
that have already been visited by the user. The other Pseudo-class state
for hyperlink visitation is :Link, which denotes a hyperlink that has not
yet been visited. A hyperlink can only be in one of these two states; after
a specific amount of time a visited hyperlink may be returned to the
unvisited state by the browser or user.