a:link – will target all of the anchors that have an href attribute.
a:visited – usually will use the same color as on the link pseudo class. Unlike Google who changes from blue (un-clicked) to purple (clicked) link.
a:hover – when your computer mouse hovers over the link, it will be styled differently.
a:active – when you actually click on the link, the style can be changed to a different background-color or font-style, for example.
text-decoration: none; (removes the underline under hyerlinks)
text-decoration: underline dotted orangered; (the underline is defined)
a:link and a:visited are very similar, so usually they are grouped together.
Link, visited, hover, and active are ALWAYS defined in this exact order.