CSS :visited selector matches all element whose href link already visited.
This CSS tutorial explains how to use the CSS selector called :visited with syntax and examples.
:visited is a pseudo-class selector that can change some of the styling on an anchor link (a) element if the user's browser has already visited the link. It's meant to help users distinguish the difference between links they have and haven't visited.
The :visited CSS pseudo-class represents links that the user has already visited. For privacy reasons, the styles that can be modified using this selector are very limited.
Styles defined by the :visited pseudo-class will be overridden by any subsequent link-related pseudo-class (:link, :hover, or :active) that has at least equal specificity. To style links appropriately, put the :visited rule after the :link rule but before the :hover and :active rules, as defined by the LVHA-order: :link — :visited — :hover — :active.
The CSS :visited selector allows you to target visited links.