The Extensible Stylesheet Language Formatting Objects (XSL-FO) is developed by the World Wide Web Consortium (W3C) and is ranked as a W3C Recommendation. It was formally called XSL because the first XSL Working Draft contained the language syntax for transforming and formatting XML documents. Sometime later, W3C split the draft into separate Recommendations such XSLT, XSL and XPath. In the new draft of XSL, the language for formatting XML documents is left and then it is called XSL-FO.

XSL-FO is an XML-based page description language for formatting XML data to appear on the screen, papers or other media. It can be used to define and design page layout, font style, colors, image rendering and lots more design properties. XSL-FO is used not only for printed documents, but also for design of multimedia documents.

The main advantage of using XSL-FO is its platform or application independence. With XSL-FO, the defined document format remains the same on any screen and any platform. For example the combination of XSL-FO and Formatting Objects Processor (FOP) allows the generation of print-ready documents in PDF, AFP, Postscript, TIFF and other formats.