A question asked by someone just like you.

What is soap made of?

Soap can be made from any animal or vegetable fat. When treated with an alkali, such as sodium hydroxide, the fat is broken down (hydrolyzed) to glycerin and alkali salts of the fatty acids. A common soap is made: sodium hydroxide + palm oil = sodium palmitate (soap) + glycerin. The glycerin and any excess sodium hydroxide can be washed away, leaving the soap.

On the farms of early America, soap was made from lard and wood ashes. Water was allowed to drip through the wood ashes to dissolve out some of the potassium hydroxide (the alkali common in wood ashes). The solution then dripped into a tub of lard. The resulting soap was mostly potassium stearate, a good soap for washing clothes but very soft compared to the sodium soaps we more commonly use today.