Basic life support (BLS) involves providing cardiopulmonary resuscitation (CPR) and using an automated external defibrillator (AED) to help someone experiencing cardiac arrest. The key components of BLS are ensuring safety, activating emergency services, performing high-quality chest compressions, opening the airway to provide rescue breaths, and using an AED to defibrillate if needed. BLS should continue until emergency medical services arrive or the victim starts breathing on their own. Early initiation of BLS, especially chest compressions and defibrillation if needed, can dramatically increase the chance of survival for someone experiencing cardiac arrest.