Chiropractic (from Greek cheira and praktikos meaning "done by hand") is a health care profession whose purpose is to diagnose and treat mechanical disorders of the spine and musculoskeletal system with the intention of affecting the nervous system and improving health. It is based on the premise that a spinal joint dysfunction can interfere with the nervous system and result in many different conditions of diminished health. While some chiropractors use the term vertebral subluxation to describe what they treat, others have dropped this concept and concentrate mostly on the musculoskeletal components of spinal injury and rehabilitation of the spine.In contrast, the term subluxation as used in conventional medicine is usually associated with specific conditions which are a direct consequence of injury to joints or associated nerves.

D. D. Palmer

Chiropractic treatments vary depending on the patient's condition and the type of approach taken by the particular chiropractor. They commonly include spinal adjustments, although other interventions may be used as well.

Today there are four main groups of chiropractors: "traditional straights", "objective straights", "mixers", and "reform". All groups, except reform, treat patients using a subluxation-based system. Differences are based on the philosophy for adjusting, claims made about the effects of those adjustments, and various additional treatments provided along with the adjustment.