School, factories, hospitals, and prisons are each institutions where discipline and power are exerted on people by gaining information about them. In such institutions, people are subjected to what Foucault calls an "examination" or a "normalizing gaze" through which information about them is then used to classify them, compare them to each other, categorize them, and ultimately subject them to discipline. The individual becomes, Foucault says, the subject of a field of knowledge, a "case." Each of these institutions is a site of a new "scientifico-disciplinary mechanism," assessing individuals in terms of their relationship to other individuals and to various norms of learning, behavior, health, and production capability.
Source: Michel Foucault, Discipine and Punish: The Birth of the Prisons (New York: Vintage Books, 1995) 170-194.