A control group is a standard in scientific experiments that helps researchers understand the effects of a treatment or intervention. It consists of participants who do not receive the treatment being tested, allowing scientists to compare their results with those who do. This comparison helps to isolate the effect of the treatment from other variables. Control groups are essential in fields like medicine, psychology, and social sciences. By using a control group, researchers can determine whether observed changes in the experimental group are due to the treatment or other factors, ensuring the validity of their findings.