This book focuses on the legal governance of online platforms concerning direct and indirect discrimination against users in the housing, advertising, and labor markets. Through an extensive investigation of sources that include private company practices, antidiscrimination policies, collective and private litigation, court decisions, and public regulation, this book illustrates how statutory law and legal precedents in the E.U. and the U.S. are only partially equipped to address discrimination against statutorily protected classes in online platforms.In the analysis of the selected sources, the author showcases that the main obstacles to the full implementation of the equality principle rely on online platforms' structural challenges, including their aesthetic designs, matching tools, evaluation systems, and network effects that ultimately reinforce old biases against protected classes. In light of these structural challenges, the author concludes that the fight against discrimination in online platforms may produce the best results when oriented by a model of regulation that encourages private businesses to implement the principle of transparency, fairness and the active cooperation of antidiscrimination bodies.