The U.S. National Science Foundation (NSF) is an independent agency of the United States federal government that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National Institutes of Health. With an annual budget of about $9.9 billion, the NSF funds approximately 25% of all federally supported basic research conducted by the United States' colleges and universities. In some fields, such as mathematics, computer science, economics, and the social sciences, the NSF is the major source of federal backing.

In the United States government, independent agencies are agencies that exist outside the federal executive departments and the Executive Office of the President. In a narrower sense, the term refers only to those independent agencies that, while considered part of the executive branch, have regulatory or rulemaking authority and are insulated from presidential control, usually because the president's power to dismiss the agency head or a member is limited.