What is "css-hover"

:hover is a pseudo-class of CSS, activated when the user interacts with a pointing device over an element (such as the cursor of the mouse, or touch the devices touch screen). The element does not necessarily need to be activated (clicked), it is sufficient that the mouse cursor is on the element (so much so that this action is also referenced as mouseover).

In many cases, by hovering the mouse over an element, such as a link, the cursor changes from an arrow to a hand with the indicator pointed upwards to indicate that the item is clickable.

Using the pseudo-class hover CSS, it is possible to customize styles when it occurs. In documentation there are some examples.