"Chiropractic is a health care profession that focuses on the relationship between the body's structure—mainly the spine—and its functioning. Although practitioners may use a variety of treatment approaches, they primarily perform adjustments (manipulations) to the spine or other parts of the body with the goal of correcting alignment problems, alleviating pain, improving function, and supporting the body's natural ability to heal itself." See more here -
http://nccam.nih.gov/health/chiropractic/introduction.htm
http://nccam.nih.gov/health/chiropractic/introduction.htm