Sulfur has been known since ancient times, used by Indians, Greeks, and Egyptians. This distinctive and often smelly element was sometimes called brimstone. Sulfur is present in garlic, a skunk's defensive spray, and is also responsible for the horrible smell of rotten eggs. Sulfur also lends strength to feathers, adds a tang to grapefruit, and is an important ingredient of fertilizer. Readers will explore sulfur from A to Z: from how it's used in matches, to how it's a critical macronutrient for every living body.