What historical change in punishment did Discipline and Punish study?

In his work Discipline and Punish, Michel Foucault examines the historical shift in the nature of punishment, specifically focusing on the transition from public, physical torture to the modern system of incarceration and surveillance.1

Foucault identifies this as a genealogical exposé of how power and knowledge—what he termed pouvoir-savoir—interact to control individuals. He argues that this shift was not merely a humanitarian improvement but a transformation in the technologies of power. The new system of "discipline" aimed to make deviance visible and manageable, seeking to manipulate and reform both the body and the soul of the individual.1

A central symbol of this disciplinary mode is the Panopticon, a prison design that allows for constant, invisible surveillance. Through this analysis, Foucault highlights how modern institutions naturalized the concept of the "criminal character" and established mechanisms of control that extend beyond the prison walls into broader society.1