Editing How to Apply Essential Oils (section)

== Basic Introduction to Essential Oils ==
'''Definition and Source:''' Essential oils generally refer to volatile aromatic molecules extracted from specific parts of aromatic plants, which are secondary metabolites of the plant. Essential oil glands can be found in plant petals, leaves, bark, rhizomes, and even fruit peels, from which the concentrated aromatic liquid essence can be extracted through appropriate methods (Essential oil - Wikipedia). These substances are volatile at room temperature and insoluble in water, hence the name essential "oil." However, essential oils do not contain fatty oil components but are primarily composed of various '''terpene compounds'''. Within the plant, essential oils help regulate growth, defend against pathogens and pests, etc.; in human applications, the aromatic properties of essential oils are used for '''mood enhancement''' and '''health and wellness''' purposes.

'''Common Types:''' There are hundreds of single essential oils available on the market, each with unique aromas and effects. For example, '''Lavender essential oil''' has a fresh, gentle scent and is known for relaxation and aiding sleep; '''Tea Tree essential oil''' has a camphoraceous odor and is often used for acne treatment and skin disinfection due to its strong antimicrobial properties; '''Peppermint essential oil''' is rich in menthol, emitting a cool, pungent aroma that can refresh the mind and alleviate headaches; '''Eucalyptus essential oil''' has a refreshing scent with camphoraceous notes and is often used to clear airways and relieve coughs (These three essential oils are respiratory tract cleaners, keep them at home! - Zhihu Column); '''Citrus essential oils''' like Lemon and Sweet Orange have bright fruity scents that can uplift mood; '''Rose essential oil''', known as the "Queen of Essential Oils," is prized in beauty for its moisturizing and antioxidant properties (Skincare Special -- Plant Essential Oils Delay Skin Aging - Zhihu Column); '''Chamomile essential oil''' has a soft, sweet aroma with soothing, calming, and anti-inflammatory effects, suitable for relieving skin sensitivity. These are just some of the common essential oils; the chemical composition and mechanism of action vary for each, requiring selection based on specific needs.

'''Extraction Methods:''' Extracting essential oils requires techniques that can release the aromatic molecules from the plant. The most traditional and common method is '''steam distillation''': plant material is boiled with water, and the steam carries the volatile aromatic components out, which are then condensed and separated to yield the essential oil (Essential oil - Wikipedia). Oils like lavender, peppermint, tea tree, patchouli, and eucalyptus are often obtained this way. For certain oil-rich fruit peels (like lemon, sweet orange), '''mechanical pressing''' is commonly used to directly squeeze out the oil (Essential oil - Wikipedia). The aromatic compounds from delicate flowers (like jasmine, tuberose) can be preserved through '''solvent extraction''' or the traditional '''enfleurage''' method. Modern industry has also developed new techniques like '''supercritical carbon dioxide extraction''', which efficiently extracts heat-sensitive aromatic substances at low temperatures. Different methods have their pros and cons, but all aim to preserve the plant's aromatic components to the greatest extent possible.