There are obvious differences in patterns of health and illness across societies, over time, and within particular society types. There has historically been a long-term decline in mortality within industrialized societies, and on average, life-expectancies are considerably higher in developed, rather than developing or undeveloped, societies. Patterns of global change in health care systems make it more imperative than ever to research and comprehend the sociology of health and illness. Continuous changes in economy, therapy, technology and insurance can affect the way individual communities view and respond to the medical care available. These rapid fluctuations cause the issue of health and illness within social life to be very dynamic in definition. Advancing information is vital because as patterns evolve, the study of the sociology of health and illness constantly needs to be updated.