Defibrillation is a medical procedure used to restore a normal heart rhythm in cases of life-threatening arrhythmias, such as ventricular fibrillation or pulseless ventricular tachycardia. It involves delivering an electric shock to the heart through the chest using a device called a defibrillator. This shock helps to reset the heart's electrical activity, allowing it to resume its normal rhythm. Defibrillation is a critical intervention in cardiopulmonary resuscitation (CPR) and is often performed in emergency situations.