Q.What is XML, and how does it differ from HTML? Give a small XML example that stores one student's roll, name and marks.

XML and HTML are both markup languages but serve opposite purposes — carrying data versus displaying it.

What XML is. XML — eXtensible Markup Language — is a markup language whose job is to store and carry data between programs, not to display it. Its power is that you can invent your own tags to label the data meaningfully (hence 'extensible').

Example — one student's data:

<student>
  <roll>21</roll>
  <name>Amit</name>
  <marks>88</marks>
</student>

Here <roll>, <name> and <marks> are tags created by the author to describe the data — there is no such thing as a <roll> tag in HTML.

How XML differs from HTML:

Thinking XML replaces HTML or is used to design web pages — it does not display anything; it carries data. Forgetting XML's strictness: leaving a tag uncl …