Once the style is defined, that style will be applied to any text enclosed within the tag, throughout the document. If the style is changed for a tag, all the text in the document using that tag will update with the new style. Style sheets can be specific to a web page, or can be stored externally and linked to by many web pages. These linked style sheets are powerful, because they enable the designer to define styles for an entire web site. If the style is changed once in the external style sheet, the changes will be reflected across the entire site.
Styles Sheets can redefine existing tags.
Style Sheets can define new tags which can be applied to any selection. Many of the styles defined in the CSS1 specification are not displayed properly inside Dreamweaver, and must be viewed in Netscape or Explorer. And of course, several of the styles display differently in Netscape and Explorer, or do not display at all in any browser. More information about each of these Style Definitions is available in the Dreamweaver Help. If you've modified a standard HTML tag, the style will automatically apply, and there is nothing to do beyond setting that tag in the normal way.