What is a control and control group?

In science, a "control group" is a group of test subjects that do not receive any of the

experimental food/ gas/ poison/ bizarre additions to their environment, etc., that the
other groups in the test do get.)


For example, if you wanted to see the effects of feeding plutonium to hamsters,


(not recommended by the way)


you would get two groups of hamsters. One group is fed the plutonium, and all effects
would be observed. (none would be good)


What you need to show what happens to ordinary hamsters over the same period of time
is called a "control group".


This would be a (luckier) group of hamsters that were not fed the plutonium.


Then you could show the differences (considerable) of the resultant effects on the two groups.