In 1902, Wilhelm Normann discovered that you could bubble hydrogen into vegetable oil to saturate it, turning polyunsaturated fat into saturated fat. Food labels often called this partially hydrogenated vegetable oil. Trans fat is less likely to go rancid. Trans fats are semisolid at room temperature, so they spread easily and have an improved mouth feel. Trans fats were ideal for deep-frying. You can use this stuff over and over without changing it.
