A CSS style rule consists of two parts—the selector and the declaration. The selector is the name of the style (such as TR, or P) and the declaration defines what the style elements are. The declaration consists of two parts, the property (such as font-family), and value (such as Helvetica).

The term cascading refers to your ability to apply multiple style sheets to the same web page. For example, you can create one style sheet to apply color and another to apply margins, and apply them both to the same page to create the design you want.

A major advantage of CSS styles is that they provide easy update capability; when you update a CSS style, the formatting of all the documents that use that style are automatically updated to the new style.