Cascading Style Sheet (CSS)
A standard for specifying the appearance of text and other elements. CSS was developed for use with HTML in Web pages. CSS is typically used to provide a single "library" of styles that are used over and over throughout a large number of related documents, as in a web site. A CSS file might specify that all numbered lists are to appear in italics. By changing that single specification the look of a large number of documents can be easily changed.