XHTML is the reformulation of HTML 4.01 in XML. XHTML 1.0 is the latest version of HTML.
CSS style sheets can be added to XML documents to provide display information.
XSL consists of three parts: XML Document Transformation (renamed XSLT), a pattern matching syntax (renamed XPath), and a formatting object interpretation.
XSLT is far more powerful than CSS. It can be used to transform XML files into many different output formats.
XPath is a language for addressing parts of an XML document. XPath was designed to be used by both XSLT and XPointer.
The XML Linking Language (XLink), allows elements to be inserted into XML documents in order to create links between XML resources.
The XML Pointer Language (XPointer), supports addressing into the internal structures of XML documents, such as elements, attributes, and content.
A DTD can be used to define the legal building blocks of an XML document.
XML namespaces defines a method for defining element and attribute names used in XML by associating them with URI references.
Schemas are powerful alternatives to DTDs. Schemas are written in XML, and support namespaces and data types.
XDR is a reduced version of XML Schema. Support for XDR was shipped with Internet Explorer 5.0 when XML Schema was still a working draft. Microsoft has committed full support for XML Schema as soon as the specification becomes a W3C Recommendation.
The DOM defines interfaces, properties and methods to manipulate XML documents.
The XML Query Language supports query facilities to extract data from XML documents.
SAX is another interface to read and manipulate XML documents.