XML vs XHTML
XML stands for EXtensible Markup Language. It is defined in the XML 1.0 specification, which is developed by the W3C (World Wide Web Consortium). XML provides a standard way, which is also simple, to encode data and text such that the content could be exchanged across driver hardware, operating systems and applications with little human intervention. XHTML (derived from eXtensible HyperText Markup Language) could be seen as combination of XML and HTML (HyperText Markup Language). XHTML is made up of the elements in HTML version 4.01, combined with the strict syntax of XML.
XML
XML is a markup language that is used to transfer data and text between driver hardware, operating systems and applications with little human intervention. XML provides tags, attributes and element structures that can be used to provide context information. This context information can be used to decode the meaning of the content. This makes it possible to develop efficient search engines and perform data mining on the data. Furthermore, traditional relational databases are suitable as XML data because they could be organized in rows and columns but XML provides less support for data with rich content such as audio, video, complex documents, etc. XML databases store data in a structured, hierarchical form which allows queries to be processed more efficiently. XML tags are not predefined and the users can define new tags and document structures. Also, new internet languages such as RSS, Atom, SOAP, and XHTM were created using XML.
XHTML
XHTML can be seen as a cleaner version of HTML, which is also stricter than HTML. XHTML is also a W3C recommendation (recommended in January, 2000) and it is a combination of HTML and XML. In XHTML, everything needs to be marked up correctly unlike in HTML. This would make sure that well formatted documents will be produced. This is very important today, since different browser technologies are widely used. This includes browsers that run on mobile devices such as phones and these browsers do not have the necessary capabilities to interpret pages with ill formatted markup languages. Therefore, XHTML that combines the strengths of XML (designed for describing data) and HTML (designed for displaying data) provides a strictly formatted markup language that avoids the above mentioned problem. All browsers support XHTML and it is compatible with HTML 4.01.
What is the difference between XML and XHTML?
XHTML is a markup language that is designed by combining XML and HTML. XML provides the extensibility to XHMTL, while requiring the XHTML documents to be well formatted unlike HTML. While XML is a markup language designed to transfer data between driver hardware, operating systems and different applications, XHTML combines the strengths of XML with HTML and provides a much cleaner and stricter markup language for creating web pages. XHTML can be seen as the future of web pages. However, XML can be used in variety of applications such as web applications communicating between different platforms and operating systems not limited to communicating with web browsers.