What is the purpose of XML?

Question

How it is used in web development?

Answer 1

XML stand for eXtensible Markup Language. It is extensible because it is a metalanguage ( a language for describing other languages, ie: SVG ).
XML to define itself use another metalanguage, SGML, the Standard Generalized Markup Language. SGML is also the language used to define Html, except for the Xhtml branch, wich was based on XML ( but was abandoned with Html5 )...

Purpose is to design specific markup languages for limitless different types of documents. 
In web context, XML improves data handling in a more accurate, flexible, and adaptable way.

Answer 2

Create a structure for positioning the elements.

Answer 3

XML is pretty similar to JSON. When computers "talk to each other "over the internet is is usually in one of those w languages.

Answer 4

Xml is a markup language (just like html) used as standard by many. So the purpose is to have a common data exchange format.