Period during which an organism loses its viability. Symptoms involve pain and suffering for patient and indirectly for family. Final period of life can also involve emotional and spiritual growth acceptance ability to transcend painful physical symptoms. Factors that influence course of life mortality can be regarded as ultimate dependent variable in study of physical and behavioural aspect of health no question on validity cause person already dead. Mostly valid indicate outcomes of particular environmental conditions/disease processes not always 100% question about validity of cause of death + debate about point at which death occurs (life support) Death = oldest sectors of population = more people alive until reach age at which death would normal occur (few child/young/middle death) Number of deaths per 100k of a particular age group. Death statistics may be incorrect because more deaths occur in smaller proportion of the population apply correction leads to age-adjusted death rate.