The technique was developed by welhelm Einthoven in 1903 .Ecg known as electrocardiograph is and instrument used for recording the functioning of the heart . the ecg works according to the electrical signal produced by the heart. The electrical signals produced by he heart during systole and diastole are collected on a graph called electrocardiogram. In ecg several electrodes are connected to he skin to transmit the electrical activity of he heart of he ecg machine. These will completed in 3 minutes. It is safe and painless. The ecg gives the information about the rate and rhythm of he heart and the functioning of heart muscles . the ecg of man consists of p wave , ors complex and t wave. The p wave is an upward deflection in the graph which indicates the depolarization of the auricles. The ors complex is a triangular wave which give the information about the ventricular depolarization. The small t wave represents eh ventricular repolarisation. Now days the multi channel monitors are used to record ecg. The ecg is used to find the rhythm of heart , cardiac ischaemia , heart attack etc.