This article deals with medicine as practiced by trained professionals from ancient times to the present. The ancient Egyptians had a system of medicine that was very advanced for its time and influenced later medical traditions. The Egyptians and Babylonians both introduced the concepts of diagnosis, prognosis, and medical examination. The Greeks went even further, and advanced as well medical ethics. The Hippocratic Oath, still taken by doctors up to today, was written in Greece in the 5th century BCE. In the medieval era, surgical practices inherited from the ancient masters were improved and then systematized in Rogerius's The Practice of Surgery. Universities began systematic training of physicians around the years 1220 in Italy. During the Renaissance, understanding of anatomy improved, and the microscope was invented. The germ theory of disease in the 19th century led to cures for many infectious diseases. Military doctors advanced the methods of trauma treatment and surgery. Public health measures were developed especially in the 19th century as the rapid growth of cities required systematic sanitary measures. Advanced research centers opened in the early 20th century, often connected with major hospitals. The mid-20th century was characterized by new biological treatments, such as antibiotics. These advancements, along with developments in chemistry, genetics, and lab technology (such as the x-ray) led to modern medicine. Medicine was heavily professionalized in the 20th century, and new careers opened to women as nurses (from the 1870s) and as physicians (especially after 1970). The 21st century is characterized by very advanced research involving numerous fields of science.

All human societies have medical beliefs that provide explanations for birth, death, and disease. Throughout history, illness has been attributed to witchcraft, demons, adverse astral influence, or the will of the gods. These ideas still retain some power, with faith healing and shrines still used in some places, although the rise of scientific medicine over the past millennium has altered or replaced many of the old beliefs.

Prehistoric medicine

Although there is no record to establish when plants were first used for medicinal purposes (herbalism), the use of plants as healing agents is a long-standing practice. Over time through emulation of the behavior of fauna a medicinal knowledge base developed and was passed between generations. As tribal culture specialized specific castes, Shamans and apothecaries performed the 'niche occupation' of healing.