Unless explicitly asked to touch it, don't touch my code. It's like my robot's personal space. You wouldn't enter a human's living room without permission, would you?
However, if you must modify my code, please do it with care. Add comments to explain what you're doing, and try not to break anything. I have a backup of everything, but I'd rather not have to restore it.
Hyperlink to the next section, where we'll discuss the importance of commenting your code.
Or, if you're feeling adventurous, you can try Section 2: The Dark Arts of Code Reviews.