A control group is a group in an experiment that does not receive the treatment or intervention being tested. Instead, it serves as a baseline to compare the effects of the treatment on the experimental group. This helps researchers determine if the treatment has a significant impact. In scientific studies, both the control group and the experimental group are treated similarly, except for the specific variable being tested. By comparing results from both groups, researchers can better understand the effects of the treatment and ensure that any changes observed are due to the treatment itself, rather than other factors.