This book presents several fundamentally new ideas. It shows that the notion of market dominance depends on the choices of firms. The fundamental idea here is to separate strategies that the firm wishes to pursue and those that it can achieve given the rival reactions. The book also highlights that consumers generally find it difficult to obtain appropriate information about the value of products when many similar products are sold on the market. Firms provide signals in the form of non-price strategies. The identification, by the consumer, of the maximum value of the product may nevertheless leave some room for firms to expand their market share beyond this.In addition, given the nature of the market, each firm has some market power with regard to consumers on the market and in its relationship with rival firms. This text presents a number of market power indices at the firm and strategy level combining these two dimensions. The book also considers issues of regulation of apps in cyberspace and discusses practical regulatory policies that have been developed to limit misuse of information in cyberspace.