The World Health Organization (WHO) is a branch of the United Nations designed to coordinate every aspect of health--physical and mental--and apply those principles on an international basis. It was originally constituted by the United Nations on April 7, 1948, now known as World Health Day, and operates in over 150 countries, containing 194 Member States. At its core, the WHO seeks to create universal health systems, provide research, treatment, and prevention for both incommunicable and communicable diseases, and arrange the health response of nations during the event of an emergency. The principal purpose of the WHO is to provide leadership on matters of critical health, to build an archive through stimulation that contains the knowledge required to combat such matters of health, and to minimize the potential risk of it occurring again. Through research, experimentation, and leadership, the World Health Organization works towards a world in which not only everyone is given healthcare and proper treatment, but also one in which the population can come together in times of critical need.