Hover is a small example of how you can add some fun little interactivity to your site. Let’s take our div example from above and add a little bit to our CSS:

div {
  color: white;
  background-color: green;
  width: 300px;
  height: 200px;
  font-family: sans-serif;
  border: 5px solid black;
div:hover {
  background-color: red;
  border: 5px dotted black;

If you apply this CSS to our border example, you will see no change at first. But if you move your mouse cursor over the div (you “hover” it), you will see the style changes applied, that we defined with the div:hover pseudo-class. There are some more pseudo-classes like that that you can learn about later.