This is the burning of an herb called Moxa. Its applied indirectly and directly to the body (for obvious reasons direct moxabustion is used infrequently). Application of fire to the body at first glance seems somewhat scary. But moxabustion feels wonderful. Most folks feel a soothing warmth. There are many techniques used. Moxa is often rolled into a cigar shape and size. The cigar is ignited and then held between a half inch and two inches from the body. This is done over an acupuncture point or along the running course of a meridian or an area that is manifesting signs or symptoms or some kind. Another frequently used technique is rolling the moxa between the fingers to mold it into a cone shape which is then placed on the area to be treated and ignited. Yet another technique is to mold the moxa into a hollow cylinder and put it on a paper base and put it over the needle handle.
Moxa is extremely Yang and imparts its Yang Qi to the patient. Some of the more obvious Yang characteristics it delivers are Heat Qi, increased Qi both locally and overall, and increased motion. Yang functions all benefit from the use of moxa. Moxa is extremely effective at moving stagnant Qi. Because so many pathologies involve stagnancy moxa is applicable to a wide variety of conditions. When it burns it releases a rather thick and heavy smoke and can make a room uncomfortable and has been known to travel through ventilation ducts and make other rooms uncomfortable. In modern times charcoaled moxa has become popular for its lack of smoke.
For all forms of moxa there are safety and therapeutic guidelines. Five to ten minutes of application on a single area is about the maximum necessary. The textbooks pretty much agree that no matter how much time has passed, if the skin becomes red application should stop. In western medicine red skin is verging on a first degree burn so I stop if the skin becomes pink. In therapeutic terms, we want the patient to feel a penetrating warmth; like standing in front of a fireplace after coming inside from cold weather.