1. A network of social, economic, or organizational structures that operate outside official or formal channels, often based on personal relationships and unwritten rules
Many developing countries rely on informal systems for trade and commerce.
Muitos países em desenvolvimento dependem de sistemas informais para comércio e negócios.
2. An underground or unofficial method of conducting business, communication, or organization that exists parallel to official institutions
The informal system of job referrals helped her find employment quickly.
O sistema informal de indicações de emprego ajudou-a a encontrar trabalho rapidamente.