Need some answers please, kinda confused..
What does this Extensible Markup Language (XML) means and what are its duty?
How do this differ to HTML?

Thanks..

XML - (eXtensible Markup Language). A widely used standard from the World Wide Web Consortium (W3C) that facilitates the interchange of data between computer applications. XML is similar to the language used for Web pages, the HyperText Markup Language (HTML), in that both use markup codes (tags). Computer programs can automatically extract data from an XML document, using its associated DTD as a guide.

HTML is another standard by itself from the W3C. but XHTML is a standards from the W3C that is an XML application. although, some people think XML is web related when it comes to designing websites, simply it is not. All XML is is a data file.

Thats just a breif overview of XML. you can go to the following like on my webpage that is called "XHTML and Stylesheets", halfway into the article it explains what XML is and what XHTML is and isnt. heres the link : http://www.dev-news.com/index.php?p=30

i hope this helps out a little.

XML HTML and XHTML all stem from SGML...Which is the Standard Generalized Markup Language...SGML is the mother tounge so to speak and XML along with HTML and a few other languages (some automated machine languages) are derivatives of SGML....

The best part about XML is that it is not only computer readable but it is also human readable...in other words it is rather easy to comunicate with the machine...

Im still learning about all of this in my spare time but a good place to start your own research would be W3Schools

Short Answer:

HTML displays web pages.
XML tags information and does not do anything. How XML is displayed depends on how a specific program wants to display it.

XML is a markup language that was, IMO, severely over-hyped about four years ago. You can create a heirarchial node structure, and then bind it to HTML elements or manipulate it with JavaScript. It's fun to play around with, but in my (admittedly limited) experience it's not of great practical value. Google has started putting it to good use with their suggest feature, and lots of people are now getting excited about the XmlHttpRequest object paired with JavaScript to create web applications that are more like desktop applications. (They've given it a pretty dumb, hypey name, though- AJAX). Some people have been doing it for years, but with Google doing it people are starting to talk more about it.

IMO the cool part of XML/JavaScript is the JavaScript... I've always thought JavaScript was so cool but it got a bad repuation for some reason, maybe because after the DHTML hype people just associated it with sliding layers, or something.

Okay, I'm done typing

HTML is markup language for text, XML is markup language for data. Most things you can do with a relational database you can do with XML, and since it is a standard, you can send your XML to someone else with no worries about compatibility.

It did get slightly overhyped, and several big businesses wentwild over it, and converted to XML entirely, only to find out that it all went much slower than the old system....

heres a goog read, hope this helps...

http://www.alistapart.com/articles/hellxml/

another thing, in case the statements above aren't clear, is that XML can tag any data. you can make your own tags if you want with XML. the real use of XML is to structure information, not just database data, but any. the key point is that data formatted in XML requires a program to PARSE it - otherwise it won't do anything. There are many standard parsers, but because xml is structured, many people can create their own programs and set how they want the the xml tagged document to appear. so much for short answers...