XPath is extremely useful when parsing and extracting information from structured data, which is encountered all the time when exploring real data. As with regular expressions, it is important to become proficient and inevitably this means getting access to powerful tools and debugging facilities.

Fortunately, there are many tools, editors, and online resources that can be used.

A good free editor that I use is Notepad++ available at http://notepad-plus-plus.org/. This has a number of plugins including an XPath evaluator.

In addition, Google spreadsheets provide a way to build real-time XPath queries, and W3Schools (http://www.w3schools.com) gives a good set of tutorials for XPath and many other Web technologies.