We had an interesting policy in the company where I worked before and I use it for my own projects: only one line is ever allowed - explaining WHAT was changed.

We had an interesting policy in the company where I worked before and I use it for my own projects: only one line is ever allowed - explaining WHAT was changed. - to explain HOW it works: comment in the code, so whoever comes to change the code later knows what should be touched and what should be left alone - to explain WHY it was changed, use the bug tracker and just supply the #ID of bug/feature request in the comment Having single-line comments makes it much easier to browse through history and find the thing you're looking for.