Extensible Markup Language

Extensible Markup Language (XML) is a set of rules in encoding document in machine readable form. XML's design goal emphasize simplicity, generality and usability over the internet. Although the design of XML focuses on documents, it is widely used for the representation of arbitrary data structures, for example in web services.

Many application programming interfaces (APIs) have been developed that software developers use to process XML data, and several schema system exist to aid in the definition of XML-based languages.
As of 2009^[update], hundreds of XML-based languages have been developed^, including RSS, Atom, SOAP, and XHTML. XML-based formats have become the default for most office-productivity tools, including Microsoft Office (Office Open XML), OpenOffice.org (OpenDocument), and Apple's iWork. 

Here I will show a simple problem in how the XML is used.

Below will be the XML Table.

Computational Method.

Molecular Mechanic	Semi Empirical	Ab Initio
Very Fast Speed	Fast Speed	Low Speed
Restriction Parameters	Good accuracy	Very Good Accuracy
Very Good Protein Modelling	Good Protein Modelling	Best Protein Modelling

From the XML Table we can change it into XML Documentation as shown below. Here I use Microsoft Word to write it.

We also can change it into XML Tree. Here I use Microsoft Power Point.

 

 We can used XML to store and transport data and use HTML to display it. So when there are any changes in the data, we just need to change it in XML and refresh the HTML to display the new changes. Thus, it is more convenient to use XML rather than HTML in storing and make changes in data.