This document provides an introduction to the topics of psychogerontology and aging. It discusses demographic changes resulting in an aging population globally. Age can be defined chronologically or biologically, and aging involves both losses and gains. Common stereotypes about aging include views of older adults as frail, dependent, isolated, unable to learn or adapt, but research shows there is variability in the aging process. Studies of aging use cross-sectional, longitudinal and experimental designs to better understand biological, psychological and social aspects of aging.