Question

what is a placebo

Answer 1

A placebo is an inactive, fake, or "dummy"

Answer 2

A harmless pill, medicine, or procedure prescribed more for the psychological benefit to the patient than for any physiological effect.

Answer 3

A placebo is a pill that's harmless, given to patients for medical research most of the times and its inactive however patients may feel the 'placebo effect', where they the doctors have told the patients that they will feel better after taking it, when they haven't really but may have better symptoms than before.

Answer 4

Yes, just like others answered, it is a "fake" in an experiment. It is useful when trying to determine the real cause of a certain effect without any bias.

Example: If patients believe they are being given real medication for an illness, and not a placebo, and they report feeling better; the experimenter/doctor can determine that the medication may not be the reason patients are feeling better, but maybe a difference in their state of mind or other factors as well.

Hope I've helped!