[eykanal]

This applies to change tracking as well... I've essentially used this message when describing to my team how to write useful Git commit messages. The diffs will tell you the where and the what, the job of the commit message is to tell you the why.

[jtbigwoo]

I've started pretending that all my commit messages will finish the statement, "I made this change because..."

[muxxa]

I agree and would go further: comments in commit messages tells you the motivation of a person at a particular point in time, while comments in the code are less trustworthy as they can go out of sync with the code. I find the usecases for in-code commenting to be very rare indeed.

[NateDad]

The whole point is the why. Yes, they can occasionally get out of sync with the code, but that should get caught in code reviews. In 2 years you'll go back to look at the code and wonder why in the hell you're stripping out the 3rd byte of that array... and only the why will tell you. The code can tell you WHAT it is doing, but you have to infer why, unless there's a comment.