http://clinicalcenter.nih.gov/participate/faqaboutcs.shtml
Patient Recruitment and Public Liaison Office, Clinical Center/NIH
Clinical studies are research studies in which real people participate as volunteers. Clinical research studies (sometimes called trials or protocols) are a means of developing new treatments and medications for diseases and conditions. This document answers frequently asked questions about clinical studies, including what a "healthy volunteer" is; what Phase I, Phase II and Phase III studies are; what safeguards are there to protect participants in clinical research; and more.