Margarine was invented in the 1860s by a French chemist as a cheap replacement for butter. Nowadays, margarine is frequently bought in the belief that it is a healthier option than butter.
All margarine contains as much fat as butter, but some are lower in cholesterol and saturated fats.
However the health benefits of many of these types of spreads has been called into question as most of them are made with hydrogenated (chemically hardened) vegetable oils and this process is believed to convert the polyunsaturated fat into trans-fats which have a negative effect on cholesterol and are now thought to be linked with heart disease even more than saturated fat.