Markup validation in general is a service that allows you to see if your code meets the requirements of the language used. When you submit your code to the validator, it will tell you what you are doing incorrectly so that you can fix it.
HTML is in XHTML, some argue that XHTML is it's own markup
XHTML stands for eXtensible HyperText Markup Language.
HTML and XHTML are both markup languages used to markup content for display on web browsers or other compatible devices. HTML stands for HyperText Markup Language and XHTML stands for eXtensible HyperText Markup Language. XHTML was created to help make HTML more XML like in structure and usage as compared to standard HTML.
Extensible HyperText Markup Language
XHTML is an aberration for Extensive Hyper Text Markup Language. It is the tighter form of HTML but is similar.
HTML - Hyper Text Markup Language and is the basic language used to program/code websites. XHTML - Extensible Hypertext Markup Language and is a family of XML Languages.
XHTML is Extensible Hyper Text Markup Language. It is a stricter form of HTML with all tags closed.
The full form of XHTML is Extensive Hyper Text Markup Language. It is a form of HTML only and is similar.
HTML XHTML SGML MathML XML GML are a few Markup Languages to name
Kelly Valqui has written: 'XHTML, level one' -- subject(s): XHTML (Document markup language)
XHTML is a markup language, not a script language which means that in fact no programming (functions etc.) happens, XHTML displays info.
The W3C (World Wide Web Consortium) is the recommended organization for code validation, particularly for HTML and CSS. Their official site, the W3C Markup Validation Service, allows developers to check the validity of their web pages by validating HTML and XHTML documents against W3C standards. Additionally, they provide a CSS Validation Service for ensuring stylesheets conform to established specifications.