XML (eXtensible Markup Language) is the Swiss Army knife of data formats, and it has become the default container for Microsoft Office, Apple iWork, XHTML, SVG, and more. XML's versatility comes with a price, as it makes XML verbose and slower. There are several ways to parse XML in Python, but xml.etree.ElementTree is recommended due to its Pythonic interface, backed by an efficient C backend. We are not going to cover XML parsing in this book, but good tutorials exist elsewhere (such as http://eli.thegreenplace.net/2012/03/15/processing-xml-in-python-with-elementtree).

As an example, the same population table can be transformed into XML:

<?xml version='1.0' encoding='utf-8'?>
<populations>
 <population>
 <Country>United Kingdom</Country> 
 <Time>1950</Time>
 <Sex>Male</Sex>
 <Age>0-4</Age>
 <Value>2238.735</Value>
 </population>
 <population>
 <Country>United States of America</Country>
 <Time>1950</Time>
 <Sex>Male</Sex>
 <Age>0-4</Age>
 <Value>8812.309</Value>
 </population>
</populations>