The control is the part of an experiment that does not change. The other parts of an experiment are constants, experimental group, independent variable and dependent variable.
Every experiment has five steps. These are make an observation, develop a hypothesis, design an experiment, conduct the experiment and analyze the results obtained, and make conclusions based upon the results obtained. The control is the part of the experiment that remains the same throughout and is what the experimental group is compared to during the experiment. The variables are what is changed and the results that are obtained based on those changes.