According to Wikipedia a Fraternity is a "word for brotherhood, and by extension deep friendship or camaraderie," and more specifically "Some types of student society, social organizations of students of higher education." They are commonly refered to as either a fraternity or sororities in Canada, the Philippines, and the United States, student corporations in Europe, and nations in Sweeden.
Wiki then explains that since the names are of two or three Greek letters, "fraternities and sororities are known collectively as the Greek System and its members as Greeks. The use of Greek letters started with the first such organization, Phi Beta Kappa, which used Greek letters to hide their secret name."
"There are various types of fraternities: social, service, professional, and honorary. Many fraternities and sororities are national organizations with chapters at individual schools. National organizations may impose certain requirements on individual chapters to standardize rituals and policies regarding membership, housing, or behavior. Members of a national fraternity or sorority may enjoy certain privileges when visiting other chapters of the same national fraternity. Other fraternities and sororities are "local" and do not belong to a national organization. Local fraternities and sororities can establish their own constitution and bylaws, and do not need to contribute financially to a national organization."
"Unique among most campus organizations, members of social fraternities and sororities often live together in a large house or apartment complex. Because of this residential situation, the individual organizations themselves at their respective schools are known as "houses". Professional, academic or honorary societies rarely maintain a permanent housing location, and some may be barred from doing so by their national organization."
A fraternity or sorority house can usually be identified by large Greek letters on the front of the house, advertising the name of the group.
At many large universities, it is traditional for Greek organizations to enjoy the use of large, Victorian style mansions on campus. In more modern times, some university administrations have sought to seize or buy out these houses and convert them into academic use or demolish them and convert them into additional parking.
A good history of the Greek System is at this Wiki Link Another Wiki Article is dedicated to Fraternity and Sorority Houses. Yet another Wiki Article is about Corporations in European Countries. There is also a Wikipedia dedicated to the Greek System called Greekopedia
This category is intended to locate all Fraternity and Sorority Houses around the world. If there is no house, the headquarters will be accepted, the description should clearly state this. Organizations must be officially sanctioned by the associated institution.