What is an experimental group and control group?

What is an experimental group and control group?|||In an experiment where you're trying to test how one thing (the independent variable - for instance a new drug) influences another thing (the dependent variable - for instance recovery from a disease) you need an experimental group in which the independent variable is applied (for instance a group of people that are given the drug), and you need another group that is treated like the first except that the independent variable is not applied (so a group given placebos). That way, if the dependent variable was affected by something other than the independent variable, that effect will show up in both groups. This lets you know what effects are directly attributable to the independent variable.