The article introduces the theory of mechanism design, which focuses on creating optimal rules for auctions, public goods provision, and exchanges. Unlike traditional game theory, which predicts player behavior based on existing rules, mechanism design selects the best rules for the game. Key findings include Myerson's theorem on revenue-maximizing auctions, the impossibility of efficient trade with hidden information, and the non-existence of dominant strategy voting mechanisms. The research offers accessible explanations of these classic results and explores current frontiers in the field.