Central Intelligence Agency (CIA) was formed on September 18 , 1947 . It is the largest of the intelligence agencies and is responsible for gathering data from other countries that could impact U.S policy . It is a civilian intelligence agency of the United States government responsible for providing national security intelligence to senior United States policymakers . The CIA also engages in covert activities at the request of the President of the United States of America . The CIA's primary function is to collect information about foreign governments , corporations , and individuals , and to advise public policymakers . The agency conducts covert operations and paramilitary actions , and exerts foreign political influence through its Special Activities Division . There are about 20,000 employees in this agency .