I've seen this a lot and I've always wondered what this means. I've always thought it meant whether or not a story was light/happy, dark/foreboding, depressing, etc. But then I've heard of the terms "taking itself seriously" and "not taking itself too seriously". That's different, right? Here's a hypothetical example. Suppose I'm writing a story set during World War II in Nazi-occupied France. Would the mood have to be dark and depressing because of the setting, or could it be kind of light and cheerful? Let's say the story focused on something entirely unrelated to the Nazis, but the setting just so happened to be set in Nazi-occupied France. Would that change the mood of the overall work? Or would it be roughly the same? In rough tangent to this: what does it mean when a story either does or doesn't take itself seriously? I assume it would if it wanted to have a good plot, but does it really mean what sort of things the plot deals with? A jewelry heist in Nazi-occupied Paris can be as serious or comedic as it wants depending on the overall story? Thoughts?