Every year, hundreds of movies are released, but only a few of them become box ofﬁce hits or blockbusters. Each of the hits accounts for hundreds of millions of dollars in revenues while many of the nonhits each account for little or nothing. Every year, thousands of books are published, but only a select few make the bestseller list. In the music industry, only a few songs go on to become hits. In all three cases, a few blockbusters, hits, or bestsellers are each responsible for millions of dollars in sales while the great majority of the products each account for only thousands or fewer dollars. This behavior can be captured by the graph of Figure 3.1 in which the vertical axis represents the sales while the horizontal axis captures the products (movies, books, songs) that bring in the revenues. As one progresses along the horizontal axis away from the origin to the right, sales start out high but tail off as one moves further away from the origin. Effectively, the graph has a long tail to the right and a short head to the left. This phenomenon in which a few get most of the action while many get very little is not limited to product sales. In the Internet, a few blogs each get thousands of visitors while thousands of other blogs get a few hits each. In a book like this one, a few words like “the” are used frequently while many others such as “consequently” are seldom used. In many countries, 80 percent of the wealth is owned by less than 10 percent of the population.