My favorite type of "What" comment is: // The following block should have the same // result as this (simpler) code: // <code> // but for <reason> th

My favorite type of "What" comment is: // The following block should have the same // result as this (simpler) code: // <code> // but for <reason> this version is better This is great for things like opaque optimizations, things that mimic a library function except for one critical difference, blocks that become really convoluted to deal with special cases, and similar.