I can try (although I admit I am too lazy to - but see below), but keep in mind that Ovid tried too in his famous node, and while that one helped me a lot, it was no substitute for the book. Regular expressions basically are (as Larry observed in the relevant Apocalypse) a language unto themselves, and noone (or so I'd hope) would expect to learn a programming language from one post on a forum. One thing that struck me as I read the book was that there are many references, both backward and forward, all over the book. I may try at some point (and then it is likely to be a series of nodes rather than just one), but I don't believe I will manage to explain the mechanics better than the book, and certainly not in as much depth.

Makeshifts last the longest.