The first thing that is required mentioning here is that prisons have four major purposes, which are incapacitation, rehabilitation, deterrence and retribution. Retribution is providing strong punishment to the criminals through depriving them of their freedom. Through incapacitation, a prison removes criminals from the society and through deterrence prison prevents anticipated future crimes. Finally, through the purpose of rehabilitation, prisons provide varied activities, which are designed for changing the behaviors of the criminals and modify them so that they can live a better life.