There’s an old software joke that goes: “Some people, when confronted with a problem, reach for regular expressions. Now they have two problems.” Regular expressions are a web developer’s best friend and worst nightmare. Sure, you’re glad someone posted the regex pattern for a phone number on Stack Overflow, but when the intern asked you to explain what a “capture group” was, you broke into a cold sweat. So is a “regex” the same thing as a regular expression? How are regular expressions implemented in JavaScript? And just what do Alan Turing and Noam Chomsky have to do with all of this?