Simon Willison’s Weblog

What are the best resources for learning regular expressions?

My answer to What are the best resources for learning regular expressions? on Quora

The O’Reilly book on Regular Expressions is absolutely superb. It will help you build a much deeper understanding if how they actually work than any online tutorial I’ve seen.

Chapter 3 of “Text Processing in Python” is excellent too, and is available for free online:

http://gnosis.cx/TPiP/chap3.txt