In this Open Access video Dr Claudia Pagliari discusses some of the ways in which data about our health is being collected and utilised, the benefits and risks this can bring for individuals and society, and the ethical dilemmas this presents. For example, health data may be used to inform better clinical decisions, understand the spread of disease in populations, spot drug side-effects, or target services to those who most need them. But it can also be highly sensitive, may predict other aspects of our lives, is vulnerable to misuse in the wrong hands and can be politically controversial. Claudia discusses the critical importance of public trust and good governance for enabling the responsible use of health data, and highlights a range of associated issues, including the rise of commercial data brokers, the challenge of 'anonymisation', how scientific timelines can make it difficult to demonstrate public benefit, and the influence of social inequalities on the 'digital privacy divide'. While the video mainly focuses on the use of data generated when we interact with healthcare institutions, Claudia points out that data about our health and wellbeing is also being captured from the 'exhaust trails' we leave behind when using digital tools and services in our daily lives, which may be harder to monitor and regulate.