15.6. The content Property plus the before and after Pseudo-Elements

There is little point in talking about the content property without also talking about the before and after pseudo-elements, since their functions are so inextricably intertwined. The content property is used to set the type of content (i.e., an HTML tag) with which the before and after pseudo-elements are associated. The content property is always used in conjunction with the before and after pseudo-classes. This collection of CSS2 functions enables Web authors to set such things as audio cues to be spoken immediately before or after certain elements, or to add formatting to specific onscreen elements.

These functions are also used extensively by all of the other properties contained within the generated content, automatic numbering and lists family.