An emergency medical service (or EMS) is a service providing out-of-hospital acute care and transport to definitive care, to patients with illnesses and injuries which the patient believes constitute a medical emergency.

The most common and recognized EMS type is an ambulance organization. EMS can encompass services developed to move critically ill patients from one facility to another (also known as Interfacility Transport or IFT), or they can respond to medical emergencies (known as 9-1-1 calls). The fire department plays a very active role in the EMS, as they are located throughout most neighborhoods in the United States. In a fire unit, there are trained firefighters able to respond to medical emergencies. Here is a more comprehensive list of different EMS organizations:

  • Government EMS – Operating separately from (although alongside) the fire and police service of the area, these ambulances are funded by local or national government. In some countries, these tend to be found only in big cities, whereas in countries such as the United Kingdom, almost all emergency ambulances are part of the NHS.
  • Fire or Police Linked Service – In many countries (USA, France, Germany, Japan), many ambulances are operated by the local fire or police service. This is particularly common in rural areas, where maintaining a separate service is not necessarily cost effective. This can lead, in some instances, to an illness or injury being responded to by a vehicle other than an ambulance, such as a fire truck. In some locales, firefighters are the first responders to calls for emergency medical aid, with separate ambulance services providing transportation to hospitals when necessary.
  • Voluntary EMS – Some charities or non-profit companies operate ambulances, which provide emergency and patient transport function. This may be along similar lines to volunteer Fire companies and is either community or privately owned. They may be linked to a voluntary fire service, with volunteers providing both services. There are also charities which focus on providing ambulances for the community, or coverage at private events (sports etc.). The Red Cross provides this service in many countries across the world on a volunteer basis (and in others as a private ambulance service), as do some other smaller organizations such as St. John Ambulance. In some countries, these volunteer ambulances may be seen providing support to the full time ambulance crews during times of emergency.
  • Private Ambulance Service – Normal commercial companies with paid employees, but often on contract to the local or national government. Many private companies provide only the patient transport elements of ambulance care (i.e. non urgent), but in some places, they are also contracted to provide emergency care, or to form a ‘second tier’ response, where they only respond to emergencies when all of the full-time emergency ambulance crews are busy or to respond to non-emergency home calls, such as “pick up and put back” calls, which are made when a person falls without injury, but needs help getting up. Dependent on their contract they might also provide “first aid only” services, such as providing bandages (but not a trip to the hospital emergency room) to a child who skinned his/her knees at a playground. They may also be contracted by private clients to provide standby EMS for large events such as sports, conventions, or parades.
  • Combined Emergency Service – Combined emergency services are full-service emergency service agencies, which may be found in places such as airports or large colleges and universities. Their key feature is that all personnel are trained not only in ambulance (EMT) care, but as a firefighter and a peace officer (police function). They may also be found in some smaller towns and cities which do not have the resource or requirement for separate services. This multi-functionality allows the community to make the most of limited resource or budget by having a single team respond to any emergency.
  • Hospital Based Service – Some hospitals may provide their own ambulance service as a service to the community, or where ambulance care is unreliable or chargeable. Their use would be dependent on using the services of the providing hospital.