[sophiabits]

Comments are often the best tool for explaining why a bit of code is formulated how it is, or explaining why a more obvious alternate implementation is a dead end.

An example of this: assume you live in a world where the formula for the circumference of a circle has not been derived. You end up deriving the formula yourself and write a function which returns 2piradius. This is as simple as it gets, not hacky at all, and you would /definitely/ want to include a comment explaining how you arrived at your weird and arbitrary-looking "3.1415" constant.