Chiropractic is an overall way of looking at the human body. It's based on the idea that the body is self-sustaining and self-healing. The body is in essence completely controlled by the brain through its connection via the spinal cord and the vast networks of nerves that make up the body. When this system is not functioning at its peak, the overall performance of the human body is lacking.
In the chiropractic world, drugs and medicine are not utilized as a form of treating a patient. While supplementation and nutrition are almost always a part of the bigger picture, drugs and prescriptions can be viewed as band-aids to treat symptoms rather than going to the source and treating the real problem.