Myocardial fat infiltration may represent a substrate for ventricular arrhythmias, and its presence has been associated with increased risk for sudden cardiac death in both ischaemic and non-ischaemic cardiomyopathies. Epicardial and pericardial adiposity has also been linked with adverse cardiovascular outcomes. Fat-water separation (FWS) is an advanced magnetic resonance imaging technique enabling for visualisation and quantification of lipid content within the myocardium, and it can also identify fat-containing neoplasms, discriminate epicardial and pericardial fat, and characterise pericardial disease. Methods for FWS have improved significantly over the years, with resulting optimisation of cardiac and extracardiac fat imaging, and resolution of artifacts that may arise from the presence of fat. This review covers the physics underlying FWS imaging technique, its evolution, the practical aspects of sequence acquisition, clinical applications, and future directions.