The Central Intelligence Agency (CIA) is a civilian intelligence agency of the United States government. Its primary function is collecting and analyzing information about foreign governments, corporations, and persons in order to advise public policymakers.

Prior to December 2004, the CIA was literally the central intelligence organization for the US government. The Intelligence Reform and Terrorism Prevention Act of 2004 created the office of the Director of National Intelligence (DNI), who took over some of the government and intelligence community (IC)-wide function that had previously been under the CIA. The DNI manages the United States Intelligence Community and in so doing it manages the intelligence cycle. Among the functions that moved to the DNI were the preparation of estimates reflecting the consolidated opinion of the 16 IC agencies, and preparation of briefings for the President.

When discussing the CIA, it is critical to understand when one is speaking of the older IC-wide responsibilities, or its present set of responsibilities. The IC still has internal politics, , although an increasing number of interagency "centers", as well as the Intellipedia information sharing mechanism, are hoped to be improvements.

The current CIA still has a number of functions in common with other countries' intelligence agencies; see relationships with foreign intelligence agencies. The agency both collects and analyzes intelligence. The CIA's headquarters is in the community of Langley in the McLean CDP of Fairfax County, Virginia, a few miles west of Washington, D.C. along the Potomac River.

Sometimes, the CIA is referred to euphemistically in government and military parlance as Other Government Agencies (or OGA), particularly when its operations in a particular area are an open secret. Other terms include The Company and The Agency.