One goal shared by many Web authors is to develop a striking layout for their Web pages and sites. Not too long ago, you could only achieve advanced layout effects using scripting languages, tables, ActiveX controls, and other workarounds that made your Web site unviewable in certain browsers. It's a mechanism by which precise formatting can be applied to HTML documents. For example, you can define the sizes of margins, indents, typefaces, etc. In short, style sheets are like the templates you use in word processing and desktop publishing applications.
Style sheets can do a lot more.
Future plans for them include printing extensions, which will let you create actual page breaks for printing Web content. In CSS-capable browsers, users will also be able to override the formatting of a particular page with their own style sheet. This is useful not only to improve the look of the Web sites you are visiting, but can help the visually impaired better access Web content. The CSS-enabled browsers that currently support this type of override are Opera 3.50, GNUscape Navigator , and Internet Explorer 4.0. You can find more information on style sheets here .