The National Science Foundation (NSF) is a United States government agency 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 $6.02 billion (fiscal year 2008), NSF funds approximately 20 percent 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, NSF is the major source of federal backing.

The NSF's director, its deputy director, and the 24 members of the National Science Board (NSB) are appointed by the President of the United States, and confirmed by the United States Senate. The director and deputy director are responsible for administration, planning, budgeting and day-to-day operations of the foundation, while the NSB meets six times a year to establish its overall policies. The current NSF director is Dr. Arden L. Bement, Jr., and the current deputy director is Dr. Kathie L. Olsen.

Grants and the merit review process

Although many other federal research agencies operate their own laboratories—notable examples being the National Aeronautics and Space Administration (NASA) and the National Institutes of Health (NIH)—NSF does not. Instead, it seeks to fulfill its mission chiefly by issuing competitive, limited-term grants in response to specific proposals from the research community. (NSF also makes some contracts.) Some proposals are solicited, and some are not; NSF funds both kinds.

NSF receives about 40,000 such proposals each year, and funds about 10,000 of them. Those funded are typically the projects that are ranked highest in a merit review process. These reviews are carried out by panels of independent scientists, engineers and educators who are experts in the relevant fields of study, and who are selected by NSF with particular attention to avoiding conflicts of interest. (For example, the reviewers cannot work at NSF itself, nor for the institution that employs the proposing researchers.) All proposal evaluations are confidential (the proposing researchers may see them, but they do not see the names of the reviewers).

Most NSF grants go to individuals or small groups of investigators who carry out research at their home campuses. Other grants provide funding for mid-scale research centers, instruments and facilities that serve researchers from many institutions. Still others fund national-scale facilities that are shared by the research community as a whole. Examples of national facilities include NSF's national observatories, with their giant optical and radio telescopes; its Antarctic research sites; its high-end computer facilities and ultra-high-speed network connections; the ships and submersibles used for ocean research; and its gravitational wave observatories.