HTML is famously known for not being a regular language. An explanation isn’t required, you can find many formal proofs online (indeed, a junior year CS student should be able to write a proof after their DS/algo/automata classes).
This very old post is funny because despite it being so famously known as being irregular, stack overflow questions kept popping up asking how to use regular expressions to parse HTML, which you can’t do.
https://en.m.wikipedia.org/wiki/Regular_language
HTML is famously known for not being a regular language. An explanation isn’t required, you can find many formal proofs online (indeed, a junior year CS student should be able to write a proof after their DS/algo/automata classes).
This very old post is funny because despite it being so famously known as being irregular, stack overflow questions kept popping up asking how to use regular expressions to parse HTML, which you can’t do.