The term Chakra comes from the Sanskrit word for wheel or turning.
In Hindu and Buddhist metaphyshical tradition Chakras are centers of life force or vital energy and correspond to the vital points in the physical body, e.g., major plexuses of arteries, veins and nerves. Various teachings provide different numbers and physical structures of chakras but in western culture 7 main chakras are normally used and associated with a certain colour. The similarities between Chinese and Indian philosophies meant that Chakras were adopted into therapies like acupuncture and acupressure which have become accepted in western medicine as useful alternative therapies.
Related Links
Chakra on Wikipedia