Fraternities and sororities are fraternal social organizations for undergraduate students. The term refers mainly to such organizations at colleges and universities in the United States, although it is also applied to analogous European groups also known as corporations. Similar, but less common, organizations also exist for secondary school students. In modern usage, the term 'Greek letter organization' is often synonymous in North America, with the terms 'fraternity' and 'sorority'. Typically, Greek letters organizations are single-sex, initiatory organizations with membership considered active during the undergraduate years only, although a notable exception to this rule are historically black, Latino, Asian, and multicultural organizations, in which active membership continues, and into which members are often initiated long after the completion of their undergraduate degrees.
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