Carrier oil is used to dilute essential oils before they are applied to the skin in massage and aromatherapy. Carrier oils transport essential oils through the skin and into the blood stream. Can also be used for skin and hair care. 

Olive oil is typically too heavy to use in most essential oil applications, but it works remarkably well when making herbal oil infusions. A few examples of these are arnica or calendula infused oils for bruising and wound healing.