Fraternities, all-male organizations, and sororities, all-female organizations, are named using Greek letters. They vary in size based on the size of the university ; I went to school at the College of William and Mary in Williamsburg, Virginia, where each organization had around 100 members.
American Universities and Greek Life by Brooke
Fraternities and sororities constitute a university experience that is singularly American. I am often asked about my involvement in Greek life by my European counterparts, so here is the low-down :