A control in an experiment is an element or group that remains unchanged and is not affected by the independent variable being tested. It serves as a benchmark or standard of comparison to measure the effects of the independent variable on the experimental group. For example, in testing a new medicine, the experimental group receives the medicine, while the control group receives no medicine or a placebo. Comparing results between these groups helps scientists isolate the effect of the medicine itself

. Controls are essential to minimize the influence of confounding variables- factors other than the independent variable that could affect the outcome. By holding other variables constant or using control groups, researchers ensure that observed effects are due to the independent variable alone, increasing the reliability and validity of the experiment

. There are different types of controls, including negative controls (expected to show no effect) and positive controls (expected to show a known effect), which help verify that the experimental setup is working properly and that results are meaningful

. In summary, a control:

• Is unaffected by the independent variable.
• Provides a baseline for comparison.
• Helps eliminate alternate explanations for results.
• Ensures experimental validity and reliability