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Dr. M H B Ariyaratne edited this page Mar 21, 2025 · 1 revision

HTML vs XHTML

This page explains the key differences, use cases, and compatibility considerations between HTML and XHTML, helping developers choose the appropriate markup language for their web projects.


Overview

HTML (HyperText Markup Language) and XHTML (Extensible HyperText Markup Language) are both markup languages used to structure web content. XHTML is a stricter, XML-based version of HTML.


Key Differences

Feature HTML XHTML
Syntax Tolerant of errors Strict XML syntax
Tag Closure Optional for some tags All tags must be closed
Case Sensitivity Tags and attributes are case-insensitive Tags and attributes must be lowercase
Attribute Quotation Quotes optional Quotes required around attribute values
Doctype Typically declared as <!DOCTYPE html> Must declare a valid XHTML DOCTYPE
Parsing Parsed by HTML parsers Parsed by XML parsers
Error Handling Browser attempts to fix errors silently Parsing fails on well-formedness errors

Compatibility

HTML is more forgiving and widely used across all browsers.

XHTML requires stricter syntax and proper content-type (application/xhtml+xml) to be correctly interpreted as XML.


When to Use

Use HTML for most web projects due to its flexibility and broad support.

Use XHTML when integration with XML tools or strict validation is required.


Best Practices

Even when using HTML, follow good practices like closing tags and quoting attributes.

For XHTML, ensure your document is well-formed and served with the correct MIME type.


Conclusion

Choose HTML for simplicity and robustness across environments.

Use XHTML if you need strict XML compliance, especially in XML-heavy applications.

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