PubMed® is a free, open-access online database from the National Library of Medicine providing research articles about medicine, health, and related fields like biology and psychology. PubMed® provides over 38 million citations and abstracts for biomedical literature from MEDLINE, the National Library of Medicine’s (NLM) main bibliographic database. It includes life science journals and online books of medicine, health, biology, psychology, and more. Although the database is free to search, some articles link to publisher websites that require payment or institutional access.