Historically, the concept of aging refers to changes to individuals that occur over time resulting from some combination of biological, psychological, and social mechanisms. The life-span developmental perspective is a somewhat broader framework, as it considers aging to begin at birth and conceptualizes human development as multidimensional and multidirectional processes of growth involving both gains and losses. From this perspective, human development and aging are embedded in multiple contexts and are conceived of in terms of dynamic processes in which the ontogeny of development interacts with the social environment, a set of interconnected social settings, embedded in a multilayered social and cultural context. In addition, the uniqueness of individual biographies and the diversity of life patterns have encouraged a life-course approach to human development within the social sciences. The study of the life course is primarily concerned with the social pathways defined by events and transitions experienced by individuals and the sequences of roles and experiences followed by individuals over particular phases of their lives. Influences of development, maturation, and aging are usually identified with changes within individuals linked to their getting older, becoming more mature as they live more of life, and having experienced a variety of different life-course events, or as a result of physical, cognitive, or other kinds of developmental change. For simplicity, we often refer to all of these types of within-person change as the effects, or consequences, of aging.