A placebo is a substance or treatment with no active therapeutic effect, often used in clinical trials to test the effectiveness of new medications or therapies. It is typically designed to resemble the actual treatment but does not contain any active ingredients. The “placebo effect” occurs when individuals experience real improvements in their condition after taking a placebo, driven by their belief in the treatment’s efficacy. Placebos are valuable in research for separating the psychological and physiological effects of treatments from their actual medicinal impact.