Old-age annuity program; Old-age insurance program; Public pension program; Retirement insurance program Definition Social security is the protection that a society provides to individuals and households to ensure access to health care and to guarantee income security, particularly in cases of old age, unemployment, sickness, invalidity, work injury, maternity, or loss of a breadwinner. Overview Demographic changes, especially population aging, have important impacts on macroeconomic variables, public sector fiscal balance, and other areas such as public pension and public health systems (Reher 2011; Mason and Lee 2007). The rapidly aging population presents one of the greatest public policy challenges around the world and raises concerns about living conditions, social support, and health care provision for older adults, especially in societies where economic development has weakened family support, and a universal welfare system is not yet in place. Population aging brings challenges not only for financing pensions, health, and long-term care, but also for the social security and public sector in general. Overall, all regions of the world, especially Europe, Asia, and Latin America, are facing impacts of demographic changes in their social security programs (Donehower et al. 2016; Rofman and Oliveri 2012; Hammer et al. 2019; see ▶ "Social Security in Latin America"; ▶ "Social Security in the US"; ▶ "Social Security: Long-Term Financing and Reform"). Public pension costs have increased fast in the last few decades, and public health costs are expected to increase rapidly in the next few years. Several countries are undergoing major pension reforms and creating incentives to longer working lives; however, there are very specific challenges for different areas of the world (Reher 2011; Börsch-Supan et al. 2015; Fleury 2017).