HTMLXHTML
HTML stands for Hypertext Markup Language.XHTML stands for Extensible Hypertext Markup Language.
It was developed by Tim Berners-Lee.It was developed by W3C i.e World Wide Web Consortium.
It was developed in 1991.It was released in 2000.
It is extended from SGML.It is extended from XML and HTML.
The format is a document file format.The format is a markup language.
All tags and attributes are not necessarily to be in lower or upper case.In this, every tag and attribute should be in lower case.