Analysis of strategic advantage using a Venn diagram (short video):
Short summary article of Competition Demystified by Greenwald and Kahn (barriers to entry create competitive advantage for managers and investors):
Barriers to entry consist of supply advantages, demand advantages, and economies of scale.
Short video criticism of Porter's Five Forces - Competition Demystified:
Short video summary of Competition Demystified:
Intangible (intellectual) property law, for example, erects legal barriers to entry for a proprietary product or service. If there are no barriers to entry then competitors enter the market easily to compete on price and volume and erode the advantage.