A stylesheet mechanism that has been specifically developed for webpage designers and users. Stylesheets describe how documents are presented on screens, in print, and even in spoken voice. Stylesheets allow the user to change the appearance of hundreds of Web pages by changing just one file. A stylesheet is made up of rules that tell a browser how to present a document. Numerous properties may be defined for an element; each property is given a value. Examples are font properties, color and background properties, text properties, box properties, classification properties, and units. The term cascading refers to the fact that more than one stylesheet can be used on the same document, with different levels of importance. Stylesheet markup is contained within or (braces); and style formatting may be integral or external (*.CSS). Although CSS2 protocols exist, the W3C has only approved CSS Level 1 for integration. There are differences between CSS and XSL (Extensible Style Language). Both languages can be used with XML, but only CSS can be used with HTML. XSL, however, is a transformation language, and can be used to transform XML data into HTML/CSS documents on a web server.