A control group acts as the standard for comparison in an experiment. It serves as a point of reference, allowing researchers to evaluate the effects of the variables they're studying. The control group is similar to the experimental groups in all respects except that it doesn't receive the treatment or intervention being tested. This similarity enables researchers to isolate and analyze the specific impact of the treatment. The control group ensures that any changes observed in the experimental group can be attributed to the independent variable being tested, rather than external factors.