Barbecue sauce is the thick, glossy, dark-red-to-mahogany American sauce built to coat grilled and smoked meat — a sweet, tangy, smoky glaze most often based on tomato, sweetened with sugar or molasses, soured with vinegar, and deepened with spice and a savoury, Worcestershire-and-smoke backbone. It is less a single recipe than a family: a handful of strongly regional styles across the American South and Midwest, from the sweet tomato "Kansas City" style most of the world means by "barbecue sauce" to thin vinegar-pepper Carolina mops and a bright yellow mustard sauce, each tuned to a particular meat and tradition.