Why cheese, specifically? The word forces your mouth into a smile-like shape. First popularized in the 1940s, photographers found that asking subjects to say "cheese" created more natural-looking expressions than "hold still and look pleasant." Today, different cultures have their own variations: "kimchi" in Korea, "whiskey" in parts of the US, and delightfully, "money" in Argentina. Our deep-dive article explores the psychology behind photographic smiling, including why your driver's license photo never quite captures your actual face, and how passport photo regulations (no smiling!) create their own special brand of awkwardness.