Consumer data has long been the currency of the digital economy – but how is its value determined, who is permitted to trade it, and when do ‘free’ offers come at a price? This volume provides a comprehensive overview: the GDPR and the Data Act, common law perspectives, the review of terms and conditions (‘ius pretium’), and the implications of monetisation for contract types and structures. In addition, the volume addresses issues of fairness beyond consumer protection, IoT data, market failure in the B2C sector, and the determination of data values (assets, data trading, databases).