This book is the result of a study of nine data brokers, representing a cross-section of the industry, undertaken by the Federal Trade Commission (FTC) to shed light on the data broker industry. Data brokers obtain and share vast amounts of consumer information, typically behind the scenes, without consumer knowledge. Data brokers sell this information for marketing campaigns and fraud prevention, among other purposes. Although consumers benefit from data broker practices which, for example, help enable consumers to find and enjoy the products and services they prefer, data broker practices also raise privacy concerns. The FTC found that data brokers operate with a fundamental lack of transparency. The Commission recommends that Congress consider enacting legislation to make data broker practices more visible to consumers and to give consumers greater control over the immense amounts of personal information about them collected and shared by data brokers.