Margarine is an artificial butter. It can be made from vegetable oil, or animal fat. It may also contain skimmed milk, salt and emulsifiers. Margarine is used in many baked products. It contains less fat than butter, so is often chosen instead of it. There are also "low fat" margarines, which contain even less fat. However, many types of margarine are made with hydrogenated oils. Products with hydrogenated oil have trans fats, which are unhealthy and can cause heart disease. Other fats, like olive oil, and butter, are a better choice for cooking.