MedlinePlus is a free website that provides consumer health information for patients, families, and Health care providers. The site brings together information from the United States National Library of Medicine, the National Institutes of Health (NIH), other U.S. government agencies, and health-related organizations. The U.S. National Library of Medicine produces and maintains the site. MedlinePlus includes a companion site in Spanish, which offers similar content for the Spanish-speaking community. It also offers a mobile site in both English and Spanish optimized for display on mobile devices. Over 150 million people from around the world use MedlinePlus each year.

MedlinePlus contains:

Throughout its history, the National Library of Medicine traditionally focused its programs and services on health care professionals. In the 1990s, the Library recognized that the general public was becoming an important user group, due to the increasing availability of Internet access. This new user group needed access to reliable health information in a consumer-friendly, Web-based format. The National Library of Medicine sought to meet this need with the introduction of MedlinePlus in October 1998.