The Freedom of Information Act [FOIA], 5 U.S.C. § 552, is a federal freedom of information law that requires the full or partial disclosure of previously unreleased information and documents controlled by the United States government upon request. The act defines agency records subject to disclosure, outlines mandatory disclosure procedures, and defines nine exemptions to the statute. The act was intended to make U.S. government agencies' functions more transparent so that the American public could more easily identify problems in government functioning and put pressure on Congress, agency officials, and the president to address them.

While the public may be aware of news organizations' use of FOIA for reporting purposes, they make up less than 10% of all requests with businesses, law firms, and individuals all being more frequent users.

A federal court has concisely described the vital role of the FOIA in democracy:

It has often been observed that the central purpose of the FOIA is to "open… up the workings of government to public scrutiny." One of the premises of that objective is the belief that "an informed electorate is vital to the proper operation of a democracy." A more specific goal implicit in the foregoing principles is to give citizens access to the information on the basis of which government agencies make their decisions, thereby equipping the populace to evaluate and criticize those decisions.

Apart from the U.S. federal government's Freedom of Information Act, the U.S. states have their own varying freedom of information laws [also know as the State Sunshine Laws].