It really depends on the type of soap you are making. Some soaps have ingredients such as palm oil while some use olive oil. Either way, most soaps today are created with lye; usually through the cold process method. Bottom line, saponification is a major factor for making soap. Saponification is the chemical reaction that takes place as a result of combining an acid and a base. This, in turn, forms a salt. You can find more information here: http://www.soap-making-resource.com/how-is-soap-made.html
