A benefit society, fraternal benefit society, fraternal benefit order, or mutual aid society is a society, an organization or a voluntary association formed to provide mutual aid, benefit, for instance insurance for relief from sundry difficulties. Such organizations may be formally organized with charters and established customs, or may arise "ad hoc" to meet unique needs of a particular time and place. Many major financial institutions existing today, particularly some insurance companies, mutual savings banks, and credit unions, trace their origins back to benefit societies, as can many modern fraternal organizations and fraternal orders which are now viewed as being primarily social; the modern legal system essentially requires all such organizations of appreciable size to incorporate as one of these forms or another to continue to exist on an ongoing basis.