Hope It would be helpful...
XHTML is a stricter and cleaner version of HTML.
Use XHTML coding it's the better than HTML...
XHTML is a combination of HTML and XML
You can checkout the major difference between three XHTML types.
Document Type Definitions (DTD)
- A DTD specifies the syntax of a web page in SGML
- DTDs are used by SGML applications, such as HTML, to specify rules for documents of a particular type, including a set of elements and entity declarations
- An XHTML DTD describes in precise, computer-readable language, the allowed syntax of XHTML markup
There are three XHTML DTDs:
- STRICT
- TRANSITIONAL
- FRAMESET
XHTML 1.0 Strict
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
Use the strict DOCTYPE when you want really clean markup, free of presentational clutter. Use it together with CSS.
XHTML 1.0 Transitional
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
Use the transitional DOCTYPE when you want to still use HTML's presentational features.
XHTML 1.0 Frameset
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Frameset//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd">
Use the frameset DOCTYPE when you want to use HTML frames.
Edit:
Major Differences b/w HTML&XHTML:
- 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 HTML, some elements can be improperly nested within each other, like this:
<b><i>This text is bold and italic</b></i> In XHTML, all elements must be properly nested within each other, like this:
<b><i>This text is bold and italic</i></b>
Note: A common mistake with nested lists, is to forget that the inside list must be within <li> and </li> tags.
This is wrong:
<ul>
<li>Coffee</li>
<li>Tea
<ul>
<li>Black tea</li>
<li>Green tea</li>
</ul>
<li>Milk</li>
</ul> This is correct:
<ul>
<li>Coffee</li>
<li>Tea
<ul>
<li>Black tea</li>
<li>Green tea</li>
</ul>
</li>
<li>Milk</li>
</ul> Notice that we have inserted a </li> tag after the </ul> tag in the "correct" code example.
XHTML Elements Must Always Be Closed
Non-empty elements must have a closing tag.
This is wrong:
<p>This is a paragraph
<p>This is another paragraph This is correct:
<p>This is a paragraph</p>
<p>This is another paragraph</p>
Empty Elements Must Also Be Closed
Empty elements must also be closed.
This is wrong:
A break: <br>
A horizontal rule: <hr>
An image: <img src="happy.gif" alt="Happy face"> This is correct:
A break: <br />
A horizontal rule: <hr />
An image: <img src="happy.gif" alt="Happy face" />
XHTML Elements Must Be In Lower Case
Tag names and attributes must be in lower case.
This is wrong:
<BODY>
<P>This is a paragraph</P>
</BODY> This is correct:
<body>
<p>This is a paragraph</p>
</body>
XHTML Documents Must Have One Root Element
All XHTML elements must be nested within the <html> root element. Child elements must be in pairs and correctly nested within their parent element.
The basic document structure is:
<html>
<head> ... </head>
<body> ... </body>
</html>