The National Academy of Sciences (NAS) is a United States nonprofit, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the National Academy of Medicine (NAM).

The National Academies of Sciences, Engineering, and Medicine (NASEM), also known as the National Academies, is a congressionally chartered organization that serves as the collective scientific national academy of the United States. The name is used interchangeably in two senses: (1) as an umbrella term or parent organization for its three sub-divisions that operate as quasi-independent honorific learned society member organizations known as the National Academy of Sciences (NAS), the National Academy of Engineering (NAE), and the National Academy of Medicine (NAM); and (2) as the brand for studies and reports issued by the unified operating arm of the three academies originally known as the National Research Council (NRC). The National Academies also serve as public policy advisors, research institutes, think tanks, and public administration consultants on issues of public importance or on request by the government.