Oleo, more commonly called margarine, is a spreadable fat made by hydrogenating vegetable oils such as soybean, palm, or canola oil into a solid or semi-solid form. It was invented in 1869 by French chemist Hippolyte Mège-Mouriès as a cheaper substitute for butter, developed for a competition sponsored by Napoleon III. Major vegetable-oil-producing regions, including the United States, Southeast Asia, and South America, supply the bulk of the raw oils used in modern margarine production. Oleo has a mild, neutral flavor and a creamy texture similar to butter, making it a common substitute in baking and cooking, particularly for dairy-free and vegan diets; some specialty versions add salt or herbs. It can be used interchangeably with butter for spreading, sautéing, and baking, though the results differ slightly since oleo contains more water and less milk fat.