This essay discusses the principles and application of punishments in an era of mass incarceration, including theories of punishment such as retributive, deterrent, preventive, incapacitation, and reformative theories. It also explores the criminal justice system and the impact of mass incarceration on society, including issues of racial discrimination and custodial deaths. The essay concludes with recommendations for maintaining effective strategies to make the environment of prisons safe and providing adequate facilities for prisoners.