For the most part HTML and XHTML have many things in common, but there are differences between the two. HTML allows for imperfect coding where XHTML does not. That is the fundamental difference between the HTML and XHTML. Also XHTML requires you to do more things such as using the ALT attribute and nesting tags. Nesting tags require for you to close the same order you opened them. XHTML also requires a valid DOCTYPE and the closing of particular tags.

10 Common Tag Changes

  1. HTML: <br> XHTML:<br />
  2. HTML:<img> XHTML:<img />
  3. HTML:<html> XHTML:<html xmlns="http://www.w3.org/1999/xhtml"><html<html mlns="http://www.w3.org/1999/xhtml""http://www.w3.org/1999/xhtml">>
  4. HTML:<hr> XHTML:<hr />
  5. HTML:<meta> XHTML:<meta />
  6. HTML:<link> XHTML:<link />
  7. HTML:<param> XHTML:<param />
  8. HTML:<input> XHTML:<input />
  9. HTML:<option> XHTML:<option /><option<option />>
  10. HTML:<col> XHTML:<col />

5 Snippets
  1. HTML:<body></body> XHTML:<body><p></p></body>
  2. HTML:<b><i></b></i> XHTML:<b><i></i></b>
  3. HTML:<table width=800></table> XHTML:<table width="800"></table>
  4. HTML:<a href="" name=""></a> XHTML:<a href="" id""></a>
  5. HTML:<blockquote></blockquote>XHTML:<blockquote><p></p></blockquote>

Web Resources
http://www.w3schools.com/
http://www.webmonkey.com/

http://webdesign.about.com/