In Attack on Titan, three distinct currencies govern survival. Silver Marks are the official government-issued money—paper notes and silver coins used to buy food, rent housing, and purchase equipment, though their value plummets in refugee camps where potatoes become the real currency. Favors operate as an invisible economy of debts and obligations between soldiers, criminals, and politicians—a saved life means someone owes you, a secret kept means you own someone, and these non-monetary debts often prove more valuable than silver when you need protection, information, or escape. Green Marks are less valuable compared to the others.