HTML vs XHTML - hmislk/hmis GitHub Wiki
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.