There are known fraternal organizations which existed as far back as ancient Greece.

The only true distinction between a fraternity and any other form of social organization is the implication that the members freely associate as equals for a mutually beneficial purpose, rather than because of a religious, governmental, commercial, or familial bond, although there are fraternities dedicated to each of these fields.

Fraternities can be organized for many purposes, including university education, work skills, ethics, ethnicity, religion, politics, charity, chivalry, other standards of personal conduct, asceticism, service, performing arts, family command of territory, and even crime. There is almost always an explicit goal of mutual support, and while there have been fraternal orders for the well-off there have also been many fraternities for those in the lower ranks of society, especially for national or religious minorities.