EMS is also synonymous with: First Aid Squad, Emergency Squad, Safety Squad, Rescue Squad, Ambulance Squad, Ambulance Corps, Life Squad or its initials spelled out, Emergency Medical Service. They usually all do the same thing but with different names, all representing the same basic thing: emergency patient care.

The goal of EMS is to provide early treatment to those in need of urgent medical care, and ultimately rapid transportation to an Emergency department. Stabilizing patients early (within the golden hour) significantly increases their chances of survival, particularly in the event of a heart attack, diabetic emergency, or severe physical trauma. Many EMT responsibilities also require the EMT to extricate the patient from where they are whether it is in a tight location in a home, or from a vehicle using the jaws of life.

EMS providers work under the license and indirect supervision of a medical director or board-certified physician who oversees the policies and protocols of a particular EMS system or organization. Due to the nature of the environment in which EMS personnel must work, equipment and procedures are necessarily limited; however, prehospital personnel are able to provide a high level of advanced care.

EMS dispatch is a dispatch center which receives calls for help and sends emergency medical technicians to respond to medical emergencies.

EMS professionals are trained to follow a formal and carefully designed decision tree, more commonly referred to as a protocol or standard of care, which has been created and approved by physicians. The emphasis in emergency services is on following correct procedure quickly and accurately rather than on making in-depth diagnoses that require much professional training and experience. The use of a decision tree allows EMS workers to be trained in a much shorter time than physicians, with EMT-Basic classes, for example, as short as 1-5 months.

National EMS standards for the US are determined by the U.S. Department of Transportation and modified by each state's Department of EMS (usually under its Department of Health), and further altered by Regional Medical Advisory Committees (usually in rural areas) or by other committees or even individual EMS providers. In addition, the National Registry of Emergency Medical Technicians, an independent body, was created in 1970 at the recommendation of President Lyndon B. Johnson in an effort to provide a nationwide consensus on protocols and a nationally accepted certification. National Registry certification is widely accepted in some parts of the U.S., while other areas still maintain their own, separate protocols and training curricula.