First published in 1980, Competitive Strategy contradicted the accepted wisdom of the time that said firms should focus on expanding their market share. Instead, Porter claimed, they should analyze the five forces that mold the environment in which they compete: new entrants, substitute products, buyers, suppliers, and industry rivals. Then they could rationally choose one of three 'generic strategies'—lowering cost, differentiating their product, or catering to a niche market—to gain a competitive edge. With its straightforward, nontechnical approach, Competitive Strategy soon became one of the most influential and frequently quoted books on business strategy.