Aromatherapy is the use of pure essential oils for healing. I find it irritating how misused this word is. Commercial retailers who use nothing but artificial fragrance oils try to convince us that aromatherapy is about smelling good-well it's not. Fragrance oils are perfumery NOT aromatherapy. There is something to be said about your environment smelling good-it does make you feel better than being somewhere that smells bad but again this is NOT aromatherapy.
Essential oils come from plants. Some are distilled with water or steam, some (citrus oils) are squeezed from the fruit peels. So beware if someone is trying to sell you "essential oil" of fresh linen. There is no such thing. I recommend that you search the web and educate yourself about the use and action of essential oils and to get a sense of pricing of various oils. That's one easy way to spot a fake. You can get a high quality Lavender oil for $12-15/oz while Rose oil would run more like $1000+ per ounce.
Two general rules about using essential oils are never to apply them undiluted on the skin and never to take them internally. But then again, never say never. Some oils like Lavender and Tea tree are perfectly safe to use undiluted on the skin (neat) while some oils like Cinnamon and Clove should probably never be used on the skin at all, even if they are highly diluted. Every oil is different. Never fall into the trap of thinking it's safe because it's natural-you should take it every bit as serious as any drug your doctor gives you! As far as internal use-I've done it and European aromatherapists practice it. The biggest problem here is that no matter how reliable your supplier is you can never be 100% sure that your oil comes from a plant that wasn't treated pesticides.
Very few essential oils are safe to use during pregnancy and I recommend not using any during the first trimester. Dosages are different for children and the elderly. Oils should never be used on infants until they are at least 2 months old. For babies you can start with Roman Chamomile, Lavender and Mandarin. Other oils can be added as the child gets older and they are able to tolerate more. DO YOUR HOMEWORK! How would you feel if you harmed your child instead of helping them?
I am always happy to answer questions about aromatherapy. It is my preferred mode of healing and I still believe it's safer than pharmaceuticals when it's used by people who have proper training. Click here to ask me questions.