The official Presidential Library system is made up of specialized libraries run by the National Archives and Records Administration (NARA), one library for each president since Herbert Hoover. The presidential libraries hold papers, records, and other historical materials from the corresponding president and are important research archives for scholars of the presidency and presidents. Many of them also have museum spaces and exhibits displaying the materials and educating the public on the president and the context in which they served. Starting with the Obama Presidential Library, the libraries have been primarily online, reflecting the born-digital nature of almost all of the material. These presidents may still have physical museums or centers as well.
Other libraries, run by independent foundations, universities, or states, exist for earlier presidents. These libraries, as well as other archives, hold the papers of earlier presidents that NARA does not have.