CSS3 understands pseudo-class selectors

A brief introduction to CSS3 pseudo-class selectors:
Before the rise of standard browsers, many beginners may be unfamiliar with pseudo-class selectors, but for The :link, :focus and :hover selectors will be familiar to you because they are often used to set link state styles. In fact, they are pseudo-class selectors.
Basic syntax of pseudo-class selector:

  selector:pseudo-class{
  property:value;
}

Structural analysis:
1.selector: other css selectors.
2.:pseudo-class: pseudo-class selector.
3.property:value: Corresponding style attribute and value.
The code example is as follows:

a:link{color:red;}
a.title:link{color:blue;}