XHTML is a stricter, more XML-based version of HTML.

What does XHTML mean?

EXtensible HyperText Markup Language, or XHTML, is what it stands for.
XHTML is a stricter version of HTML that uses more XML.
XHTML is HTML that has been made into an XML application.
All of the major browsers can read XHTML.

Why XHTML?

XML is a markup language where all documents must be marked up correctly (be “well-formed”) (be “well-formed”).

XHTML was made so that HTML could be used with other data formats in a more flexible way (such as XML). Also, browsers don’t care about mistakes on HTML pages and will try to show the website even if it has mistakes in the markup. So XHTML comes with a much stricter error handling.

Please read our XML Tutorial if you want to learn more about XML.

What’s Most Different from HTML?

1. <!DOCTYPE> is mandatory
2. The html> tag must have the xmlns attribute.
3. html>, head>, title>, and body> must all be present.
4. Elements must always be nested in the right way.
5. Elements must be closed at all times.
6. Elements always have to be in lowercase
7. The names of attributes must always be in lowercase.
8. The value of an attribute must always be quoted.
9. Attribute minimization is forbidden

# Summary

Here is what you've learned in this lesson:

• What does XHTML mean?
• Why XHTML?
• What's Most Different from HTML?