An ECG (electrocardiogram) is a non-invasive recording of the heart’s electrical activity obtained through surface electrodes placed on the skin. It is essential in clinical practice for diagnosing arrhythmias, myocardial ischaemia, and conduction abnormalities by analysing wave patterns and intervals. For example, ST-segment elevation on an ECG is a critical indicator of acute myocardial infarction requiring urgent intervention.