Great questions, I struggled with this part the most when I was learning it. `.grad` is set by `autograd` when calling `backward()` Probably the easiest way t

Great questions, I struggled with this part the most when I was learning it. `.grad` is set by `autograd` when calling `backward()` Probably the easiest way to understand this is to play a bit with `.grad` and `backward()` on their own, with the first code sample in the `autograd` section [1]. [1]: https://sirupsen.com/napkin/neural-net#automagically-computing-the-slope-of-a-function-with-autograd https://sirupsen.com/napkin/neural-net#automagically-computi...