Social security , also called social welfare, is any of various programs designed to provide a population with income at times when they are unable to care for themselves. The model for modern government social security programs was developed in 1883 by Otto von Bismarck under the title soziale Sicherheit.

A distinction is made between Social security and social welfare systems in many countries.

Social security is seen as providing assistance to retired workers, often in the form of a Superannuation scheme that provides a pension, that workers have contributed to throughout their working lives. Workers may also contribute to some form of insurance scheme that provides income and assistance in the event of injury or illness for them and their families. While the scheme may be compulsory, the contributions or historic income often determine the level of support provided, once basic eligibility criteria such as age or inability to work are established.
Social welfare is generally seen as financial assistance provided to those who have basic needs, such as food, clothing and housing, but are unable to afford those basic needs due to poverty or lack of income because of unemployment, sickness, disability, or caring for children. While assistance is often in the form of financial payments, those eligible for social welfare can often access health and educational services free of charge. The amount of support is enough to cover basic needs and eligibility is often subject to a comprehensive and complex assessment of an applicant's social and financial situation.