fraternities and sororities often have groups at many different schools. each fraternity or sorority is given two or three greek letters to call themselves, for example, αφ (alpha phi) or αχω (alpha chi omega). to tell the difference between groups at different schools, called chapters, each chapter is given another set of greek letters. for example, a man in the kappa sigma fraternity who goes to the university of louisiana at lafayette is part of the fraternity's ex (epsilon chi) chapter. chapters sometimes have houses on or near the campus of the college the members attend that members can live in.