EMS stands for Emergency Medical Services, which are emergency services that provide urgent pre-hospital treatment and stabilization for serious illness and injuries and transport to definitive care. EMS is a vital component of healthcare, public health, and public safety, and it responds to calls for help 24/7 in almost every community in the United States.

EMS is most recognizable by its vehicles, helicopters, and workforce, which respond to emergency incidents. Ambulances are the primary vehicles for delivering EMS, though squad cars, motorcycles, aircraft, boats, fire apparatus, and others may be used. An emergency medical dispatcher is also called an EMD, and they provide "pre-arrival" instructions to callers reporting medical emergencies.

EMS clinicians are highly skilled pre-hospital clinicians who respond to emergencies in need of urgent medical care. They work side-by-side with public safety colleagues in law enforcement and the fire service, with the primary mission of providing emergency medical care. EMS saves lives from heart attacks, strokes, and drowning; treats injuries due to motor vehicle collisions, shootings, stabbings, and other violence; and provides care for the myriad of other illnesses and injuries that occur daily in the United States.

EMS is not limited to medical emergencies, and it often responds to calls for help from homeless or indigent people, or those having a mental health or substance abuse crisis. EMS also helps communities pick up the pieces when big incidents hit, whether natural or man-made.

It is important to note that EMS is not limited to emergency medical care. Environmental Management Systems (EMS) are a set of processes and practices that enable an organization to reduce its environmental impacts and increase its operating efficiency. An EMS is a framework that helps an organization achieve its environmental goals through consistent review, evaluation, and improvement of its environmental performance. The EMS itself does not dictate a level of environmental performance that must be achieved, and each organizations EMS is tailored to its own individual objectives and targets.