Essential oils are completely natural, concentrated liquid fragrances extracted from parts of aromatic plants. They therefore contain no additives or synthetic chemicals.
To successfully extract the essential oil from the plant, two main methods are used: steam distillation and cold pressing. Steam distillation is the most common. Cold pressing is preferably used when you want to extract the oil from citrus fruits. See the article "How to make essential oils?" to learn more.
Remember that although essential oils are completely natural, they are very strong and should not be used undiluted directly on the skin! Enjoying their fragrance by adding a few drops to an Evoroma diffuser is a good, simple and safe method.