Stable angina is chest pain or discomfort caused by transient myocardial ischaemia due to fixed atherosclerotic coronary artery narrowing, typically triggered by exertion or stress and relieved by rest or nitrates. It matters clinically as it indicates underlying coronary artery disease and helps guide risk stratification and management to prevent progression to acute coronary syndromes. A key association is its potential to progress to unstable angina or myocardial infarction if plaque stability changes or occlusion worsens.