How does computer know that `^\w+\d$` should match "java8" but not "jvm15"? There must be some magic that allows a computer to recognise that certain strings match the pattern, right? Yes and we, geeks, love learning how such magic works!

Join me on a highly technical journey through the internals of regex engines. First, we will analyse ancient scripts explaining the theory - finite automata and regular languages. Then we will hack through thickets of various regex flavours to arrive at the cave of regular expression engine where we'll explore deep recesses of performance corner-cases. To add a bit of an adventure we'll intentionally fall into a trap of exponentially slow patterns and crash a real app. Finally, we'll read inscriptions left by the survivors of Stackoverflow and Cloudflare outages, both caused by regular expressions.

It's a geeky talk and you'll learn geeky stuff: how a small and neat language of regular expression is implemented and interpreted. But it's not all in vain: you'll be able to optimise the performance of regular expressions and prevent your app from being killed by a badly-crafted regex.