What it is
Palm Kernel Acid is a mixture of fatty acids derived from palm oil.
What it does
Palm Kernel Acid is a surfactant: it helps water mix with oil and dirt so they can be rinsed away.
It can also be used as an emulsifier: it prevents the oily and water parts of a formula from separating.
Finally, it adds opacity to soaps and cleansers.
Palm Kernel Acid is generally considered to be safe.