Dwg: Article written and Venn diagram created.

2026-02-19T12:32:01Z

Article written and Venn diagram created.

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== Comparison Article ==
{{Short description|Comparison of web markup languages}}

'''HTML''' (HyperText Markup Language) and '''XHTML''' (Extensible HyperText Markup Language) are markup languages used to structure and present content on the World Wide Web. While they share similar element names and purposes, they differ in their underlying syntax and technical constraints. HTML is an application of [[Standard Generalized Markup Language]] (SGML), whereas XHTML is a reformulation of HTML as an application of [[XML]].

== Development and history ==
The [[World Wide Web Consortium]] (W3C) published the first version of the XHTML 1.0 specification in January 2000. It intended to replace HTML 4.01 by providing a more rigorous structure that could be parsed by standard XML tools. During the mid-2000s, the W3C focused on XHTML 2.0, which was not backward compatible with previous web standards. This led to a schism in web development, resulting in the formation of the [[WHATWG]], which developed the "HTML Living Standard" that eventually became HTML5.

== Technical differences ==
The primary distinction between the two languages lies in the strictness of their syntax. HTML allows for certain shortcuts, such as omitting closing tags for specific elements (e.g., <code><p></code> or <code><li></code>) or using "tag soup" formatting that browsers attempt to correct during rendering.

In contrast, XHTML requires documents to be "well-formed" according to XML rules. This means every element must be explicitly closed, and empty elements must use a trailing slash (e.g., <code><br /></code>). XHTML is also case-sensitive, requiring all element and attribute names to be in lowercase, whereas HTML is case-insensitive.

=== Comparison table ===
{| class="wikitable"
|-
! Feature !! HTML !! XHTML
|-
| Document Type || Based on SGML || Based on XML
|-
| Case Sensitivity || Case-insensitive || Case-sensitive (lowercase required)
|-
| Closing Tags || Optional for some elements || Required for all elements
|-
| Attribute Quoting || Optional if no spaces are present || Mandatory for all values
|-
| Empty Elements || Written as <code><br></code> || Written as <code><br /></code>
|-
| Error Handling || Forgiving; browsers repair markup || Strict; parsing fails on errors
|-
| Attribute Minimization || Allowed (e.g., <code>checked</code>) || Prohibited (e.g., <code>checked="checked"</code>)
|-
| MIME Type || <code>text/html</code> || <code>application/xhtml+xml</code> or <code>text/xml</code>
|}

[[File:Venn_diagram_Differences_between_HTML_versus_XHTML_comparison.png|thumb|center|800px|alt=Venn diagram for Differences between HTML and XHTML|Venn diagram comparing Differences between HTML and XHTML]]

== Parsing and MIME types ==
Most browsers determine how to parse a document based on the [[media type]] (MIME type) sent by the web server. If a document is served as <code>text/html</code>, the browser uses an HTML parser, even if the code follows XHTML syntax. True XHTML requires the <code>application/xhtml+xml</code> MIME type. When a browser encounters a syntax error in a true XHTML document, XML specifications dictate that the browser should stop processing the page and display an error message, rather than attempting to guess the author's intent as an HTML parser would.

== Convergence in HTML5 ==
Current web development practices under the HTML5 standard have largely merged these two approaches. HTML5 defines both an HTML syntax and an XML-compatible syntax (often called XHTML5). While the strict requirements of XHTML are less common in modern front-end development, the principles of well-formed code are still used in various data exchange formats and content management systems.

== References ==
<references>
[1] World Wide Web Consortium. (2000). "XHTML 1.0 The Extensible HyperText Markup Language (Second Edition)". W3C Recommendation.
[2] MDN Web Docs. (2023). "HTML vs. XHTML". Mozilla Foundation.
[3] WHATWG. (2024). "HTML Living Standard: Section 1.6 - HTML vs XML".
[4] Berners-Lee, T., & Connolly, D. (1995). "Hypertext Markup Language - 2.0". IETF RFC 1866.
</references>

[[Category:Comparisons]]

Differences between HTML and XHTML - Revision history

Dwg: Article written and Venn diagram created.