Antitrust laws are designed to keep markets competitive by checking business activities posing a threat to free-market competition. The main antitrust concern with competition reflects a fundamental belief that economic questions are generally best determined in the American economy through a process of independent, competitive decision-making by profit-seeking firms that strive to serve customers. Antitrust law aims to protect economic competition by prohibiting collusive, exclusionary, and monopolistic practices that restrain competition. The main U.S. antitrust law is the Sherman Antitrust Act. Section 1 of the Act makes it illegal for sellers of a product to join together to raise the price of the product being sold. Section 2 of the Act makes monopolizing acts illegal.