Essential oils are very concentrated and can not be used directly on the skin, as they can cause irritation. Therefore essential oils are diluted before being applied, into carrier oils. Extracted from nuts, kernels, seeds, and are sometimes called vegetable oils. Burt's Bees uses several carrier oils including: Sweet Almond, Apricot Kernel, Avocado, Grape seed, Olive, Vitamin E oil, and Wheat Germ Oil.