A certified first responder is a person who has completed a course and received certification in providing pre-hospital care for medical emergencies. Certified individuals should have received much more instruction than someone who is trained in basic first aid and cardiopulmonary resuscitation (CPR) but they are not necessarily a substitute for more advanced emergency medical care rendered by emergency medical technicians and paramedics. First responders typically provide advanced first aid level care, CPR, and automated external defibrillator (AED) usage. The term "certified first responder" is not to be confused with "first responder", which is a generic term referring to the first medically trained responder to arrive on scene and medically trained telecommunication operators who provide pre-arrival medical instructions as trained Emergency Medical Dispatchers (EMD). Many police officers and firefighters are required to receive training as certified first responders. Advanced medical care is typically provided by EMS, although some police officers and firefighters also train to become emergency medical technicians or paramedics.

Emergency medical services (EMS), also known as ambulance services or paramedic services, are emergency services that provide urgent pre-hospital treatment and stabilisation for serious illness and injuries and transport to definitive care. They may also be known as a first aid squad, FAST squad, emergency squad, ambulance squad, ambulance corps, life squad or by other initialisms such as EMAS or EMARS.