The National Film Registry is meant to preserve up to 25 "culturally, historically or aesthetically significant films" each year; to be eligible, films must be at least 10 years old. The films do not have to be feature-length or to have had a theatrical release. The Foundation's primary mission is to save so-called "orphan films," films without owners to pay for their preservation. The films most at-risk are newsreels, silent films, experimental works, films out of copyright protection, significant amateur footage, documentary films, and features made outside the commercial mainstream. Hundreds of American museums, archives, libraries, universities, and historical societies care for "orphaned" original film materials of cultural value. As of 2003, there were 375 films preserved in the National Film Registry.