Welfare is a type of government support intended to ensure that members of a society can meet basic human needs such as food and shelter. Social security may either be synonymous with welfare, or refer specifically to "social insurance" programs, which provide support only to those who have previously contributed (e.g. most pension systems), as opposed to "social assistance" programs, which provide support on the basis of need alone (e.g. most disability benefits). The International Labour Organization defines social security as covering support for those in old age, support for the maintenance of children, medical treatment, parental and sick leave, unemployment and disability benefits, and support for sufferers of occupational injury.