The ClinicalTrials.gov website provides current information about clinical research studies to patients, their families and caregivers, health care professionals, and the public. Each study record includes a summary of the study protocol, including the purpose, recruitment status, and eligibility criteria. Study locations and specific contact information are listed to assist with enrollment. (See How to Read a Study Record to learn more about the information found in a study record.) Information on ClinicalTrials.gov is provided and updated by the sponsor or principal investigator of the clinical study. Clinicaltrials.gov is a free service of the National Institutes of Health (NIH) and is maintained by the National Library of Medicine (NLM).