Human Factors and Ergonomics (HFE) is a discipline concerned with designing interactions in sociotechnical systems to improve both system performance and human well-being. This Element introduces the core principles of HFE, tracing its development from multidisciplinary efforts to solve practical problems in military operations during the Second World War to its current application in healthcare improvement. The Element acknowledges the growing role of HFE in areas such as the design of the physical environment, medical device design, learning from patient safety incidents, and safety investigations. A critical reflection highlights persistent challenges, including conceptual ambiguity, structural and practical barriers to HFE integration, and the need both for a stronger evidence base and a compelling business case. The Element concludes by identifying future priorities for advancing HFE in healthcare, including continuing professional development and career pathways, embedding HFE in regulation and policy, and adopting evaluation approaches suited to complex systems. This title is also available as open access on Cambridge Core.