Osteopathy is a medical discipline that is based on the philosophy that all body systems are interrelated and dependent upon one another for good health. This philosophy, developed in 1874 by Dr. Andrew Taylor Still, recognizes the concept of "wellness" and the importance of treating illness within the context of the whole body. Special attention is placed on the musculoskeletal system. 
Osteopathic medicine is a superset of ostopathy; an osteopathic physician has full training in conventional medicine but also is trained in ostopathic techniques. Pure osteopathy has largely disappeared in the U.S., but is not uncommon in the U.K.
Osteopathy was founded on the American frontier and its initial development was regionally focused in the West. "Still was trained in orthodox medicine before the Civil War. He spent most of his training in an apprenticeship under a local doctor with didactic work for an unknown period of time in Kansas City"  He was devastated by the loss of three of his children from meningitis and derived a new system of medicine based on spinal manipulation, Christian faith, and abstinence from alcohol.
Relationship between Osteopathy and Allopathy in the Nineteenth Century
Osteopathy in the 20th Century
The Flexner Report- 1910
Abraham Flexner was an open admirer of the European (particularly German) system of higher education and an open critic of any medical practices that were not based on science.
The American Osteopathic Association urged adoption of the standards that Flexner proposed in Schools of Osteopathy.
In the U.K., it is defined as an alternative method of "Group 1", or Professionally Organised Alternative Therapies: A system of diagnosis and treatment, usually by manipulation, that mainly focuses on musculo-skeletal problems, but a few schools claim benefits across a wider spectrum of disorders. Historically differs from chiropractic in its underlying theory that it is impairment of blood supply and not nerve supply that leads to problems. However in practice there is less difference than might be assumed. Mainstream osteopathy focuses on musculo-skeletal problems; but prior to osteopathy gaining statutory protection of title, other branches of this therapy purported to diagnose and treat a range of disorders. One such branch is now known as cranio-sacral therapy, which should be considered as a distinct therapy which would fall into Group 3.
Holistic philosophy of medical practice
It has been argued that the use of spinal manipulation may play a key role in the training of DOs as holistic physicians,"the true value of spinal manipulation far exceeds its diagnostic and therapeutic value; these techniques have helped define a holistic bedside manner that is impossible to teach didactically."(reference for quote:Burke, Martin C. The DOs: Osteopathic Medicine in America (review) Perspectives in Biology and Medicine - Volume 48, Number 4, Autumn 2005, pp. 618-621)
- Medical Subject Headings, National Library of Medicine
- Burke, Martin C. (Autumn 2005), "The DOs: Osteopathic Medicine in America", Perspectives in Biology and Medicine 48 (4): 618-621
- Select Committee appointed to consider Science and Technology, U.K. Parliament (21 November 2000), Chapter 2: Disciplines examined, Definitions of the Various CAM Therapies, Complementary and Alternative Medicine