Basic life support (BLS) is a level of medical care which is used for patients with life-threatening illness or injury until the patient can be given full medical care. It can be provided by trained medical personnel, including emergency medical technicians, and by laypersons who have received BLS training. BLS is generally used in the pre-hospital setting, and can be provided without medical equipment.

Advanced life support (ALS) implies that an emergency medical technician (EMT) is capable of performing advanced life support skills as either an EMT-A (Advanced), EMT-I (Intermediate) or an EMT-P (Paramedic), commonly referred to simply as a paramedic or medic. ALS (in most cases) refers to the skills and knowledge that a practitioner possess. The ALS provider may perform advanced procedures and skills on a patient involving invasive and non-invasive procedures. In Pennsylvania, ALS can only be provided by paramedics.

A paramedic is a medical professional, usually a member of the emergency medical services, who primarily provides pre-hospital advanced medical and trauma care. A paramedic is charged with providing emergency on-scene treatment, crisis intervention, life-saving stabilization and transport of ill or injured patients to definitive emergency medical and surgical treatment facilities, such as hospitals and trauma centers. In countries such as the United States and the United Kingdom, the use of the word paramedic is restricted by law, and the person claiming the title must have passed a specific set of examinations and clinical placements, and hold a valid registration (in the UK, with the Health Professions Council), certification, or license with a governing body.

EMTs are trained to assess a patient's condition, and to perform such emergency medical procedures as are needed to maintain a patient's airway with adequate breathing and cardiovascular circulation until the patient can be transferred to an appropriate destination for advanced medical care. Interventions include cardiopulmonary resuscitation, defibrillation with an A.E.D., controlling severe external bleeding, preventing shock, body immobilization to prevent spinal damage, and splinting of bone fractures.