The National Library of Medicine (NLM), the world's largest biomedical library, produces trusted health information used by health professionals, students, researchers, innovators, medical librarians, and the public to advance medicine and improve public health.

The National Center for Biotechnology Information (NCBI) is part of the United States National Library of Medicine (NLM), a branch of the National Institutes of Health (NIH).

Many articles that you find in PubMed will say Free Article or Free PMC Article. This means that the full text of the article is freely available to the public. Two reasons articles could be freely available are: (1) because part or all of the funding for that work came from the NIH.

The National Center for Biotechnology Information (NCBI) develops and maintains molecular and bibliographic databases as a part of the National Library of Medicine (NLM). They do not generate their own data, but they do: Receive data submissions from researchers.