Haha, I will quote the text of a response I made to wegs this pm on this subject, on another forum we both subscribe to. Wegs had posted a link explaining that soap is made from fats, by a process called "saponification" (from Latin sapo, saponis, meaning....soap! ). I commented: "Fats are mainly esters of fatty acids, bonded to an alcohol called glycerol (="glycerine"). Saponification of a fat breaks these bonds , liberating the fatty acids (and the gylcerol but this is not important to what follows). However as strong alkalis, such as sodium or potassium hydroxide are used to break the bonds, the fatty acids get neutralised in the process, so you end up with a fatty acid salt, e.g. sodium or potassium stearate, rather than stearic acid. The acid salt end of the molecule has a chemical group - COO⁻ on it, which is polar and can form hydrogen bonds with water. So that end is attracted to water (hydrophilic). The other end is just a hydrocarbon chain, which is repelled by water (hydrophobic) but is attracted to oils and grease. Hence its detergent action, as PhDemon has explained. There are many other classes of synthetic detergents, used for laundry, dishwashing etc, using a wide variety of chemistry, but all share the essential feature of molecules with a hydrophilic part and a hydrophobic part." So your explanation is good. Please Register or Log in to view the hidden image!