XHTML Four Basic Elements

Four elements that must be in each page. These elements form a skeleton of the page.


XHTML start tag. First element in the page.
Header start tag. Always follows the XHTML element. Second element in the page.

XHTML VS HTML - Difference between HTML, XHTML

What Is XHTML?

• XHTML stands for EXtensible HyperText Markup Language
• XHTML is almost identical to HTML 4.01
• XHTML is a stricter and cleaner version of HTML
• XHTML is HTML defined as an XML application
• XHTML is a W3C Recommendation of January 2000.
• XHTML is supported by all major browsers.

Bad HTML

Bad HTML
This is a paragraph

The Most Important Differences from HTML:

• XHTML elements must be properly nested
• XHTML elements must always be closed
• XHTML elements must be in lowercase
• XHTML documents must have one root element

XHTML Elements Must Be Properly Nested

In XHTML, all elements must be properly nested within each other, like this:
This text is bold and italic

XHTML Elements Must Always Be Closed

Non-empty elements must have a closing tag.
This is wrong:

This is a paragraph

This is another paragraph
This is correct:

This is a paragraph

This is another paragraph

Empty Elements Must Also Be Closed

Empty elements must also be closed.
This is wrong:
A break:

A horizontal rule:

---

An image:
This is correct:
A break:

A horizontal rule:

---

An image:

XHTML Elements Must Be In Lower Case

Tag names and attributes must be in lower case.
This is wrong:


This is a paragraph


This is correct:


This is a paragraph

XHTML Documents Must Have One Root Element

All XHTML elements must be nested within the root element. Child elements must be in pairs and correctly nested within their parent element.
The basic document structure is:

…
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Source: http://www.psd-to-xhtml-conversion.com/review/xhtml-tutorials/http://www.psd-to-xhtml-conversion.com/review/xhtml-tutorials/