Chiropractic is a form of alternative medicine concerned with the diagnosis and treatment of mechanical disorders of the musculoskeletal system, especially the spine, under the belief that such a disorder affects general health via the nervous system.
It is the largest alternative medical profession. The main chiropractic treatment technique involves manual therapy, especially manipulation of the spine, other joints, and soft tissues, but may also include exercises and health and lifestyle counseling.
The "specific focus of chiropractic practice" is chiropractic subluxation. Traditional chiropractic assumes that a vertebral subluxation or spinal joint dysfunction interferes with the body's function.

Systematic reviews of this research have not found evidence that chiropractic manipulation is effective, with the possible exception of treatment for back pain. A Cochrane review found very low to moderate evidence that spinal manipulation therapy was any more effective than inert interventions, sham-SMT (therapist-assisted range of motion), or as an adjunct therapy for acute low back pain.
Spinal manipulation may be cost-effective for sub-acute or chronic low back pain, but the results for acute low back pain were insufficient.
The efficacy and cost-effectiveness of maintenance chiropractic care are unknown. The evidence suggests that spinal manipulation therapy is safe, but the rate of adverse events is unknown as there is under-reporting. It is frequently associated with mild to moderate adverse effects, with rare cases of serious or fatal complications. There is controversy regarding the degree of risk of stroke from cervical manipulation.

Chiropractic overlaps with other manual-therapy professions, including massage therapy, osteopathy, and physical therapy. Most who seek chiropractic care do so for low back pain, and back and neck pain are considered the specialties of chiropractic, but many chiropractors treat ailments other than musculoskeletal issues.

Adapted from Wikipedia, the free encyclopedia. Internet. Accessed on June 14, 2016.