How essential oils are extracted and used
Most essential oils are produced by steam distillation, which passes steam through plant material to release and carry its aromatic compounds, later separated from the resulting water. Citrus oils are typically cold-pressed from the peel instead. Once extracted, oils are used via diffusion (dispersed into room air, often with water in an ultrasonic diffuser), diluted topical application (mixed with a carrier oil for massage or skin application), or, less commonly and with more caution, ingestion — which should only be done under qualified guidance, since many oils are unsafe to consume.
Common essential oils and their traditional uses
See the panel alongside this section for a set of the most widely used oils — Lavender, Peppermint, Eucalyptus, Tea Tree, Lemon, and Frankincense — and what they're traditionally used for.
Diffusion versus topical use
Diffusion disperses the oil's aroma into the air for inhalation, generally considered the gentlest and most accessible method — commonly used for mood, sleep, or general ambiance. Topical use applies diluted oil directly to skin, typically for localized effects (like peppermint for tension or tea tree for minor skin concerns), and always requires dilution in a carrier oil to avoid irritation.
Safety basics
Never apply essential oils undiluted ("neat") to skin without first checking the specific oil's guidance, as many can cause irritation or sensitization; always patch-test a new oil; certain oils carry cautions during pregnancy, for young children, or around pets — cats in particular metabolize some plant compounds poorly; citrus oils can increase skin photosensitivity; and essential oils should never be assumed safe simply because they are "natural" — concentration matters far more than origin.