As with all herbs, it's used for multiple things, particularly in formula. The two main uses most people know it for is support for the liver and an anti-inflammatory. It is also sometimes used for digestion. As a hot herb, it would be used to increase circulation. To research this yourself, look up a good herbal -- there are many -- and for traditional uses, research ayurvedic medicine.
Anti-inflammatory. Among other ailments it is good for asthma.