A control group is a group of individuals or subjects in an experiment that does not receive the experimental treatment or intervention. This group serves as a baseline for comparison to the group that does receive the treatment, allowing researchers to determine the effectiveness of the intervention. The control group is essential in ensuring the validity and reliability of the results of an experiment. It provides a standard against which the effects of the treatment can be measured, allowing for a more accurate understanding of the impact of the intervention. In other words, the control group acts as a control variable, helping to eliminate any confounding factors and providing a clear comparison to the experimental group. Without a control group, it would be difficult to draw meaningful conclusions from an experiment.