Sometimes here on Academia I read messages referring to [American National Science Foundation (NSF)][1], "the USA agency that supports fundamental research and education in all the non-medical fields of science and engineering" ([page on Wikipedia][2]).

In [this question][3] and [this question][4] we discussed about NSF postdoctoral funding possibilities. Since I am in the European Union, I don't know very much about NSF. 

- **How does NSF funding system work?**
- How does NSF postdoctoral funding program work? Does it fund only American citizens or anyone that wants to work as a researcher in the US?

Many thanks!

  [1]: http://www.nsf.gov
  [2]: http://en.wikipedia.org/wiki/National_Science_Foundation
  [3]: https://academia.stackexchange.com/questions/986/how-do-you-grow-your-own-post-doc-opportunity
  [4]: https://academia.stackexchange.com/questions/1994/can-i-apply-for-a-post-doc-in-global-studies-in-north-america