What exactly is an 'essential' oil?

Essential oils are extracted from flowers, fruits, leaves or seeds to capture the aromatic "essence" of the plants that they come from. The result is a super-concentrated oil that can be breathed in, massaged on, or added to lotions or bath water.

The idea is that these botanical scents target smell receptors in the nose, triggering effects that pass through the nervous system to the brain. When absorbed by the skin, some oils are also thought to have antifungal or antibacterial effects.

A word of caution: Some manufacturers sell essential oils that can be taken internally, but the practice is controversial since safety research is limited.