Clinical trials are research studies that test new medical treatments, drugs, or devices on people. They help determine if these interventions are safe and effective. Participants in clinical trials may receive the new treatment or a placebo, which is an inactive substance, to compare results. These trials are conducted in phases, starting with small groups and gradually increasing in size. Each phase has specific goals, such as assessing safety, dosage, and overall effectiveness. Regulatory bodies like the U.S. Food and Drug Administration (FDA) oversee these trials to ensure ethical standards and participant safety are maintained.