The document discusses the concept of economic efficiency and the conditions required for it. It also discusses how competitive markets can achieve economic efficiency through the "invisible hand" mechanism, where individual self-interested actions by buyers and sellers lead to an outcome where marginal benefit equals marginal cost. Specifically, it notes that in a competitive market, buyers will buy until marginal benefit equals price, producers will supply until marginal cost equals price, and there will be a single market price where marginal benefit and marginal cost are equal.