It Started with XSL
XSL stands for EXtensible Stylesheet Language.
The World Wide Web Consortium (W3C) started to develop XSL because there was a need for an XML-based Stylesheet Language.
CSS = Style Sheets for HTML
HTML uses predefined tags. The meaning of, and how to display each tag is well understood.
CSS is used to add styles to HTML elements.
XSL = Style Sheets for XML
XML does not use predefined tags, and therefore the meaning of each tag is not well understood.
A <table> element could indicate an HTML table, a piece of furniture, or something else - and browsers do not know how to display it!
So, XSL describes how the XML elements should be displayed.
XSL - More Than a Style Sheet Language
XSL consists of four parts:
- XSLT - a language for transforming XML documents
- XPath - a language for navigating in XML documents
- XSL-FO - a language for formatting XML documents (discontinued in 2013)
- XQuery - a language for querying XML documents