Jeffrey Friedl's regular expression book (mentioned at the top of the article) is fantastic and I highly recommend it. If you want to not only learn regular exp

Jeffrey Friedl's regular expression book (mentioned at the top of the article) is fantastic and I highly recommend it. If you want to not only learn regular expressions, but have them be clear upon first glance and now how to optimize them based on your regular expression engine's implementation, then his book is gold. The first half is about using them, and the second half is focused on optimizing. You can skip the second half and still get a lot out of it, but it really is some fantastic stuff.