Practical differences in code, from HTML to XHTML

Practical differences in code, from HTML to XHTML

The following list summarizes the major code differences between HTML and XHTML: 

• Including the processing instruction line (the XML prolog) is recommended, but not required:

 

• Doctype declaration is required:

 

• Namespace designation is required:

 

• Html, head, body, and title elements are required:




 

  

• Tags and attributes must be lowercase:


 


• Attribute values must be quoted:

font-size="large" 

• Non-empty tags must be terminated with a closing tag:

text
 

• Empty tags (e.g., hr, br, img) must incorporate a slash:


 

• Elements can't overlap—they must nest properly:

text