XHTML namespace - World Wide Web Consortium (W3C)
Sep 7, 2016 · The namespace name http://www.w3.org/1999/xhtml is intended for use in various specifications such as: Recommendations:
XHTML - Wikipedia
The namespace URI for XHTML is http://www.w3.org/1999/xhtml. The example tag below additionally features an xml:lang attribute to identify the document with a natural language:
HTML Versus XHTML - W3Schools
XHTML was developed to make HTML more extensible and flexible to work with other data formats (such as XML). In addition, browsers ignore errors in HTML pages, and try to display the website …
What does "<html xmlns="http://www.w3.org/1999/xhtml">" do?
You're mixing up HTML with XHTML. Usually a <!DOCTYPE> declaration is used to distinguish between versions of HTMLish languages (in this case, HTML or XHTML). Different markup languages will …
XHTML - W3docs
XHTML ( EXtensible HyperText Markup Language), developed by World Wide Consortium (W3C) in 2000, is the more extended version of the popular HTML. It is the same HTML but defined as an …
XHTML - Glossary | MDN
Nov 13, 2025 · XHTML is a term that was historically used to describe HTML documents written to conform with XML syntax rules. The following example shows an HTML document and …
XHTML ™ 1.0: The Extensible HyperText Markup Language
Nov 24, 1999 · XHTML 1.0 provides the basis for a family of document types that will extend and subset XHTML, in order to support a wide range of new devices and applications, by defining modules and …
XHTML Reference: html
This attribute is required and the value should be http://www.w3.org/1999/xhtml. (Text) This attribute has been deprecated (made outdated). It is redundant, because version information is now provided by …
HTML html xmlns Attribute - W3Schools
Note: The HTML validator at http://w3.org does not complain when the xmlns attribute is missing in an XHTML document. This is because the namespace "xmlns=http://www.w3.org/1999/xhtml" is default, …
HTML <html> xmlns Attribute - GeeksforGeeks
Jul 12, 2025 · The HTML <html> xmlns Attribute is used to specify the XML namespace for a document. This attribute is mainly required in XHTML, not valid in HTML 4.01, and optional in HTML 5. Syntax …