The disease is a disease process and the consequent status of a living condition, characterized by an alteration of the ontological status of health. The state and / or disease process can be caused by many factors, both intrinsic and extrinsic sick body: these factors are called insults (from the Greek nous, “disease”, “health condition”). Health and illness are an integral part of life, biological processes and environmental and social interactions. In general, understands the disease as opposed to a health institution, whose negative effect is the result of an alteration or disproof of a system at any level (molecular, physical, mental, emotional, spiritual, etc..) Physiological state and / or morphological considered normal, balanced or harmonic (see homeostasis).By definition, there is a single disease, but the characterization and identification of various processes and different states of health, has led to discrimination against a universe of entities other than (disease entities), many of them are strictly understood as diseases, but other not (cf. syndrome, a clinical entity and disorder). In this way, disease and substitutes and similar processes are understood as categories identified by the human mind. The diseases that affect plants and other botanical plant pathology concerning the diseases that affect animals are the domain of Veterinary Science. The human disease is the core organizer of Medical Science, since much of medical knowledge is oriented toward the disease and its solution.Strictly (in the medical field), diseases are being studied of Pathology (from Greek “condition”, “suffering”) to investigate the characteristics of each entity, its components and the process developed in conjunction with morphophysiological evidence that is printed on the biology of the patient. However, discipline Nosology charge of governing the definition and classification of various diseases according to standards based on the characterization and identification of components and functions that define each disease entity as unique and distinguishable from the rest. So, are studied in a broader context, comparative, and systematic, within an overall pattern of pathology. “The Doctor” of Sammuel Luke Fildes (1891).