What are The most easier and most Difficult topics you've come across in your solo learning list them please?

Question

I believe that most of us are experiencing some difficulties in some topics so lets join hand and list them so that if anybody have any idea on how to make them easier or any advice should come forward to share it with us.

Answer 1

JavaScript DOM was new for me. Took me 2 days to understand it fully.

Answer 2

that's great...