An Anonymous Coward writes "Amazon has a much greater market share among online bookstores compared to the greatest market share for offline stores. How is this possible? Because the web changes how people find information. There are millions of links to Amazon on the web, which makes it more likely for people to find Amazon when surfing the web, or when using search engines which typically use link popularity in ranking. This makes it harder for new businesses to compete. Researchers have discovered that across the entire web, links are distributed according to a "power law" which leads to "rich get richer" or "winner's take all" behaviour where a small number of sites get the vast majority of links and traffic. A new study just released by NEC shows that this behaviour varies in different communities, and shows how to predict competition in different areas. For example, you can see how much tougher competition is among booksellers compared to photographers."