What Are Essential Oils

Essential oils (e.o.) are highly concentrated odoriferous liquid components of aromatic plants obtained usually by distillation of plant material. Sometimes they are called essences or volatile oils. There are three main methods of e.o. extraction, and the steam distillation is most common. More about this is at the bottom of the page.
Several e.o. blends sold on this site are associated with Dr. Robert Pappas, who used to be a consultant for the major essential oil network marketing company, and created Essential Oil University in 1998.

Word of Caution: the Myths
It is also important not to be seduced by misleading marketing tactics of high pressure sales companies that created several myths among their sales people. Here are the few, explained in more detail by Dr. Pappas:
"If you use a pure essential oil on your skin and it causes a rash or burn then its just your body detoxing" - not true. If you get a rash you are sensitive to a given oil and you should immediately stop applying it on your skin.
"Essential oils are complex mixtures containing hormones, vitamins, minerals and other natural elements are the most oxygenating substances on earth" - ridiculous claim. E.o. do not contain hormones, vitamins, minerals and oxygen that is capable to oxygenate tissues (that is, deliver oxygen). Although there are some e.o. may mimic certain hormones or may have effect on hormone production (for example Vitex e.o.)
"Essential oils have the highest frequency of any natural substance known to man" - it is a scam that makes no scientific sense.
"Company X is the only company in the world who sells pure or therapeutic grade essential oils" - really? There are several companies that produce high quality e.o., and the phrase "therapeutic grade" is a new buzzword created by MLM people (more on the links listed below).

More myths you can find on EOU page and Weedemandreap page.

Methods of e.o. Extraction
The most common is steam distillation, where steam of boiled water is passed through the plant material. Because the process is performed at nearly atmospheric pressure the steam is not hotter than 100 °C. This is important because no oils that boil at higher than water boiling temperature are extracted. The co-distilled with water oils are light and their boiling point is lower than water's, hence the name volatile or etheric oils.
Another popular method is cold pressing, used when oily plant components are abundant, such as citrus skin. Oils extracted this way contain components that boil at wide ranges of temperatures, as no oily components are left out from the final product. Some could be large molecules resembling carrier oils.
The third method is solvent extraction. Plant material is immersed in a solvent that could be alcohol, hexane, ether, carbon dioxide and others, and oils from a plant solubilize in those solvents. The oily mixture is than separated from the solvents. This is sometimes the only method to avoid degradation of volatile plant components as this process can be done in much lower temperatures than boiling water. Essential oils obtained this way are called absolutes. Absolutes are very different than e.o. obtained by steam distillation, and they are usually heavier as they contain high molecular compounds that boil at higher than 100 °C. Solvents can also be carrier oils, and the final products are called macerates (these mixtures often contain smaller percentages of actual essential oils).
The last two methods yield usually less healthy e.o. because they contain higher molecular weight compounds including lipopolysaccharides that easier initiate allergies and also may have traces of undesired solvents.

E.O. Contents
There are usually several different oily components, sometimes over hundred, in a single e.o. extracted from a plant. They can be categorized by chemical groups or residues covalently bound to hydrocarbon chains of e.o. components. Here are some examples. Alcohols, usually antiseptic and stimulating;
Aldehydes, anti-inflammatory, anti-viral, calming, vasodillators, skin sensitizing;
Coumarines, sedative, antifungal, phototoxic;
Esters, calming, very fragrant;
Ketones, mucolytic, sedative, analgesic;
Phenols, strongly antiseptic, stimulating, skin irritants;
Terpenes, antiseptic, analgesic, stimulating, calming, spasmolytic;