XSLT, for XML transformations, and its companion XPath, were published in November 1999: using these technologies an XML file can be transformed into any other type of XML file, for example into XHTML or SVG, for the purpose of presentation.
XHTML 1.0, which features the semantics of HTML 4.01 using the syntax of XML, became a Recommendation in January 2000.
A major step forward was made with the publication of XML Schema structures and datatypes in May 2001. XML Schemas provide functionalities above and beyond what is provided by DTDs and are essential in defining complex XML applications.
XHTML 1.1, the modularized version of XHTML, was published in May 2001. The modularization of XHTML makes it possible to develop various XHTML profiles, well adapted to particular device types or user communities.
Xlink and XML Base, both published in June 2001, define a general hyperlinking vocabulary to XML.
SMIL 2.0 will play a vital role in the new generation of internet-aware phones. It was published in August 2001.
SVG 1.0: Scalable Vector Graphics (SVG) 1.0, was published in September 2001. SVG is a major breakthrough in bringing vector graphics to the Web. Based on XML, editable by any text editor and manageable by search engines, SVG provides a rich graphics content and animation facilities, offering a strong alternative to the usage of bitmaps images.
XML-Signature: published in February 2002, is an important step towards the Web of trust. It defines an XML-based framework to add digital signatures to resources on the Web.