Machine learning is a difficult theoretical background and the techniques are so broad and diverse that it seems like you study a lot in the wide range at first, but you can't use it at all (just like studying English grammar to your heart's content and not being able to converse at all). Janjaemi Coding's lectures organize theories easily and make them usable first (they become a stepping stone for studying difficult theories). I recommend Janjaemi Coding's lectures to those who are studying machine learning for the first time or those who have studied it before and seem to know the difficult theories but have trouble implementing them (knowing and being able to do are different things).