Emergency medicine is a medical specialty involved in a full spectrum of undifferentiated physical and behavioral disorders associated with the initial evaluation, diagnosis, treatment, and disposition of any patient requiring expeditious medical, surgical, or psychiatric care. It also deals with the prevention, diagnosis and management of acute and urgent aspects of illness and injury. It encompasses an understanding of the development of pre-hospital and in-hospital emergency medical systems and the skills necessary for their development. It focuses on the immediate decision making and action necessary to prevent death or any further disability both in the pre-hospital setting by directing emergency medical technicians and in the emergency department. Practitioners provide immediate recognition, evaluation, care, stabilization and disposition of a generally diversified population of adult and pediatric patients.