Emergency medical services are a branch of emergency services dedicated to providing out-of-hospital acute medical care and/or transport to definitive care, to patients with illnesses and injuries which the patient, or the medical practitioner, believes constitutes a medical emergency. Emergency medical services may also be locally known as: first aid squad, emergency squad, rescue squad, ambulance squad, ambulance service, ambulance corps or life squad. The goal of most emergency medical services is to either provide treatment to those in need of urgent medical care, with the goal of satisfactorily treating the problem or illness, or arranging for timely removal of the patient to the next point of definitive care. This is most likely an emergency department at a hospital or another place where physicians are available. The term Emergency Medical Service evolved to reflect a change from a simple transportation system (ambulance service) to a system in which actual medical care occurred in addition to transportation In most places in the world, the EMS is constituted by members of the public (or other emergency services, businesses or authority) via an emergency telephone number which puts them in contact with a control facility, which will then dispatch a suitable resource to deal with the situation. In some places and as in Orange County, EMS units may handle technical rescue operations such as extraction, water rescue, and search and rescue. Training and qualification levels for members and employees of emergency medical services vary widely throughout the world. In some systems, members may be present who are qualified only to drive the ambulance, with no medical training. In contrast, most systems have personnel who retain at least basic first aid certifications, such as Basic Life Support (BLS). Additionally many EMS systems are staffed with Advanced Life Support (ALS) personnel, including paramedics, nurses or, less commonly, physicians.