Many patients move between providers, teams, and settings over the course of their healthcare journey. These transitions of care are increasing in frequency as populations age, chronic diseases become more prevalent and provider work patterns move towards shorter shifts and larger care teams. Poorly executed transitions of care are a risk to patient safety and may contribute to duplication of tests, a higher cost of care and negative experiences for patients and providers. Despite the increasing relevance of care transitions to health systems, significant gaps in our understanding of these complex processes persist. The potential benefits of the digital healthcare revolution have not been realised. This thesis seeks to identify, measure, and better understand transitions of care by tapping into healthcare 'big data' sources, and to highlight the role digital technologies can play in improving these processes. The first part of this thesis provides a background to transitions of care and highlights how patients sit at the centre of care transitions. A qualitative interview study of patients transferring between hospitals identifies continuity of care and communication as key priorities for patients as they move between providers. The second part of this thesis uses hospital administrative big data to measure interhospital transitions of care in the NHS in England, identifying several barriers to care continuity in existing systems of care. The third part of this thesis examines transitions of care at the level of the clinician and patient within hospitals, tapping into electronic health record data to more accurately measure and better understand the hospital teams that care for patients. The final chapter of this thesis reports on the design of a digital interactive medical record interface that aims to improve care continuity and put patients at the forefront of their care transitions.