Introduction

Extensible Markup Language—also known as XML—is a structure for representation of data in human readable format. Contrary to its name, it's actually not a language but a markup which focuses on data and its structure. XML is a lot like HTML in syntax except that where HTML is used for presentation of data, XML is used for storing and data interchange.

Moreover, all the tags in an XML are user-defined and can be formatted according to one's will. But an XML must follow the specification recommended by W3C.

With a large increase in distributed applications over the Internet, XML is the most widely used method of data interchange between applications. Web services use XML to carry and exchange data between applications. Since XML is platform-independent and is stored in string format, applications using different server-side technologies can communicate with each other using XML.

Consider the following XML document:

From the above document, we can infer that it is a list of websites...