An XSL processor reads the XML document and follows the instructions in the XSL style sheet, then it outputs a new XML document or XML-document fragment.
This is extremely useful in e-commerce, where the same data need to be converted into different representations of XML. Not all companies use the exact same programs, applications and computer systems.
XSLT Recommendation was written and developed by the XSL Working Group and became ratified by the W3C on November 16, 1999.