The National Science Foundation (NSF) supports both basic research and education in the nonmedical sciences and engineering. Congress established the foundation as an independent federal agency in 1950 and directed it to "promote the progress of science; to advance the national health, prosperity, and welfare; to secure the national defense; and for other purposes." The NSF is a primary source of federal support for U.S. university research, especially in certain fields such as mathematics and computer science. It is also responsible for significant shares of the federal science, technology, engineering, and mathematics (STEM) education program portfolio and federal STEM student aid and support. This book includes information about the NSF for readers seeking an introduction to the foundation and its work. It is intended to provide background and institutional context for ongoing congressional consideration of NSF policy and fiscal issues. It also analyzes NSF funding trends and selected closely related STEM education policy issues in order to place conversations about NSF's budget in a broader fiscal and policy context.