First, let's talk about what it is. Aromatherapy uses the natural oils existing in plants (barks, stems, flowers, etc.) and extracts them into an extremely concentrated form called "essential oils". Have you ever peeled an orange and had juice squirt from the skin of that orange? Did your hands smell like that orange for a long time after? That's the essential oils and the compounds that comprise them.
The benefits of essential oils are extensive. All of them support various bodily functions and systems. A good portion of them even kill bacteria and fungi. For example: Lavender essential oil is an analgesic and anti-inflammatory; which makes it a wonderful way to relieve pain form sore muscles. Additionally, it also helps disinfect and heal wounds, induce relaxation and sleep, aid respiratory health, aid immune health, and boost circulation. Lavender is the "go to" essential oil! Our bodies benefit when it enters the blood stream. This happens through breathing it in (which is immediate) or can be absorbed into the skin and, from there, into the blood stream (which takes about 20 minutes). Your skin isn't the only part of the body that will thank you!