The abbreviation XSLT stands for EXtensible Stylesheet Language Transformations. It is an XML-based programming language developed by the World Wide Web Consortium (W3C). XSLT transforms well-formed XML documents into XHTML or to other XML documents. However, the original XML document is left unchanged.

For the transformation, the XSLT processor selects and matches the XML Data with the help of an XSLT stylesheet, transforms it, and then produces an output document in another file format like XHTML, SVG, VRML, etc. XSLT Stylesheets include templates and template rules describing how the elements of the XML file should be processed on screens or in print. XSLT Stylesheets are well-formed XML documents.

XSLT uses XPath technology to find information in an XML document. With XPath, XSLT follows the simple tree-structured data model of XML documents and navigates through the elements and the attributes.

There are two versions of XSLT in use today: XSLT 1.0 and XSLT 2.0. XPath 1.0 should be used with XSLT 1.0 and XPath 2.0 with XSLT 2.0.