I learnt regex when I started with PHP in the 2000s and subsequently when I learned Perl. When I started studying copmuter science at the university, I was supp

I learnt regex when I started with PHP in the 2000s and subsequently when I learned Perl. When I started studying copmuter science at the university, I was supper baffled that there is a full theory of regular expressions: The one of a regular (formal) language (https://en.wikipedia.org/wiki/Regular_language https://en.wikipedia.org/wiki/Regular_language). I recommend everybody who's interested in "looking behind the curtains" of regexp, their powers and limitations, to dive in a crash course of formal languages (Chomsky hierarchy). It can be useful to gain a feeling what a regexp can do and what it cannot.