If someone tells you they made a soap without using this, I hate to tell you this- but they lied. All bar soaps are made with sodium hydroxide, also known as "caustic soda". All soap really is is the outcome of a chemical reaction that occurs when a high alkali (the lye) reacts to an oil, but with a well made soap there is no lye remaining in the finished product.

One wise soaper compared it to baking a cake.When you first mix the batter you have your flour, eggs, sugar, oil, etc. When you beat it all together it is still just batter- not something you would probably want to eat. (Unless it's chocolate! Hehe..) Anyway, the point is when you put that batter in the oven, the heat creates a chemical reaction and cooks the batter. When that batter comes out of the over it's no longer your original ingredients just stirred together- it's something entirely new. Cake! It's a similar idea with soap, only the process is called saponification.

Even liquid soap or "shower gels" are made with a form of lye called potassium hydroxide, or "caustic potash". Sometimes instead of using the ingredient "sodium hydroxide" on a label, people or companies may use the terms "saponified olive oil", "saponified palm oil", etc. It is the very same thing- just a different way of listing ingredients.