html is server side or client side scripting language
Server-side scripting Server-side scripting is a technique used in web development which involves employing scripts on a web server which produce a response customized for each user's (client's) request to the website. The alternative is for the web server itself to deliver a static web page. Scripts can be written in any of a number of server-side scripting languages that are available (see below). Server-side scripting is distinguished from client-side scripting where embedded scripts, such as JavaScript, are run client-side in a web browser, but both techniques are often used together.
XHTML XHTML was developed to make HTML more extensible and increase interoperability with other data formats.[8] In addition, browsers were forgiving of errors in HTML, and most websites were displayed despite technical errors in the markup; XHTML introduced stricter error handling.[9] HTML 4 was ostensibly an application of Standard Generalized Markup Language (SGML); however the specification for SGML was complex, and neither web browsers nor the HTML 4 Recommendation were fully conformant to it.[10] The XML standard, approved in 1998, provided a simpler data format closer in simplicity to HTML 4.[11] By shifting to an XML format, it was hoped HTML would become compatible with common XML tools;[12] servers and proxies would be able to transform content, as necessary, for constrained devices such as mobile phones.[13] By using namespaces, XHTML documents could provide extensibility by including fragments from other XML-based languages such as Scalable Vector Graphics and MathML.[14] Finally, the renewed work would provide an opportunity to divide HTML into reusable components (XHTML Modularization) and clean up untidy parts of the language.[15]