A carrier oil is a vegetable oil derived from the fatty portion of a plant, usually from the seeds, kernels or the nuts. If applied to the skin undiluted, essential oils, absolutes, CO2s and other concentrated aromatics can cause severe irritation or reactions in some individuals. Carrier oils are used to dilute essential and other oils prior to application. They carry the essential oil onto the skin. Each carrier oil offers a different combination of therapeutic properties and characteristics. The choice of carrier oil can depend on the therapeutic benefit being sought.