XHTML [ex eych tee em ell]
XHTML is an acronym for Extensible Hypertext Markup Language and is sometimes known as HTML 4.0. It is very similar to HTML, however, it is able to comply with XML syntax rules.
XML [ex em ell]
XML is an acronym for Extensible Markup Language. It allows for the creation of customized markup languages. It is typically used for web documents.
XML Document [ex em ell dok yoo muhnt]
An XML document is a document written with XML.
XSL [ex ess ell]
XSL is an acronym for Extensible Style Language. This language is made up of three parts. XSLT, or extensible stylesheet language transformations, allow the user to change the structure and format of a markup following specific rules. XSL-FO, or extensible stylesheet language formatting objects is used to create a format that can be reliably printed. XPath ensures the elements selected conform to XSLT rules.
XQuery [ex kweer ee]
XQuery describes the rules used in obtaining information from documents created using XML.