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 US$7.0 billion (fiscal year 2012), the NSF funds approximately 24% 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. 

The NSF's director and deputy director are appointed by the President of the United States, and confirmed by the United States Senate, whereas the 24 presidentially appointed members of the National Science Board (NSB) do not require Senate confirmation. 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, confirmed in March 2014, is astronomer France A. Córdova, former president of Purdue University. 

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