CSS also defines a number of pseudo-classes. Here's a sampling of pseudo-classes that can act as selectors:
:focus— Refers to the element with the focus (the item that is the target of keystrokes). For example, P:focus selects the <P> element with the focus.
:first-child— Refers to the first child of the indicated element. For example, P:first-child selects the first child of the <P> element.
:link :visited, :active, :hover—, Refer to hyperlink-like elements. The :link pseudo-class refers to elements that have been designated as links, :visited specifies the style of visited links, :active specifies the style of links as they're being activated, and :hover specifies the style as the mouse hovers over them.
:lang()— Refers ...