Margarine is a vegetable oil-based fat that was created as a less expensive alternative to butter. Indeed the composition of margarine is very similar to butter, about 80% fat and 15% water, so the two can be used interchangeably. The earliest margarines can be traced back to mid-nineteenth century France. They were composed of beef fat mixed with water and milk solids for a butter-like flavor. When hydrogenation was invented around 1900, food scientists dispensed with the beef fat and moved to the purely vegetable-based formula we know today.