the panopticon is a prison building designed by english philosopher jeremy bentham in the late eighteenth century. the design allows the observer to view all prisoners without the prisoners being able to tell if they are being observed or not.
"hence the major effect of the panopticon: to induce in the inmate a state of conscious and permanent visibility that assures the automatic functioning of power. so to arrange things that the surveillance is permanent in its effects, even if it is discontinuous in its action; that the perfection of power should tend to render its actual exercise unnecessary; that this architectural apparatus should be a machine for creating and sustaining a power relation independent of the person who exercises it; in short, that the inmates should be caught up in a power situation of which they are themselves the bearers. to achieve this, it is at once too much and too little that the prisoner should be constantly observed by an inspector: too little, for what matters is that he knows himself to be observed; too much, because he has no need in fact of being so. in view of this, bentham laid down the principle that power should be visible and unverifiable. visible: the inmate will constantly have before his eyes the tall outline of the central tower from which he is spied upon. unverifiable: the inmate must never know whether he is being looked at at any one moment; but he must be sure that he may always be so. in order to make the presence or absence of the inspector unverifiable, so that the prisoners, in their cells, cannot even see a shadow, bentham envisaged not only venetian blinds on the windows of the central observation hall, but, on the inside, partitions that intersected the hall at right angles and, in order to pass from one quarter to the other, not doors but zig-zag openings; for the slightest noise, a gleam of light, a brightness in a half-opened door would betray the presence of the guardian. the panopticon is a machine for dissociating the see/being seen dyad: in the peripheric ring, one is totally seen, without ever seeing; in the central tower, one sees everything without ever being seen."
excerpt from 'panopticism' in michael foucault: discipline & punish: the birth of the prison.