A fraternity or fraternal organization is an organization, society, club or fraternal order traditionally of men associated together for various religious or secular aims. Fraternity in the Western concept developed in the Christian context, notably with the religious orders in the Catholic Church during the Middle Ages. The concept was eventually further extended with medieval confraternities and guilds. In the early modern era, these were followed by fraternal orders such as Freemasons, the Rosicrucian Society of England, and Odd Fellows, along with gentlemen's clubs, student fraternities, and fraternal service organizations. Members are occasionally referred to as a brother or – usually in a religious context – frater or friar.

A guild is an association of artisans and merchants who oversee the practice of their craft/trade in a particular territory. The earliest types of guild formed as organizations of tradespeople belonging to a professional association. They sometimes depended on grants of letters patent from a monarch or other ruler to enforce the flow of trade to their self-employed members, and to retain ownership of tools and the supply of materials, but most were regulated by the local government. Guild members found guilty of cheating the public would be fined or banned from the guild. A lasting legacy of traditional guilds are the guildhalls constructed and used as guild meeting-places.