The Panopticon is a type of institutional building designed by the English philosopher and social theorist Jeremy Bentham in the late 18th century. The concept of the design is to allow all (pan-) inmates of an institution to be observed (-opticon) by a single watchman without the inmates being able to tell whether or not they are being watched. Although it is physically impossible for the single watchman to observe all cells at once, the fact that the inmates cannot know when they are being watched means that all inmates must act as though they are watched at all times, effectively controlling their own behaviour constantly. The name is also a reference to Panoptes from Greek mythology; he was a giant with a hundred eyes and thus was known to be a very effective watchman.
The design consists of a circular structure with an "inspection house" at its centre, from which the manager or staff of the institution are able to watch the inmates, who are stationed around the perimeter. Bentham conceived the basic plan as being equally applicable to hospitals, schools, sanatoriums, daycares, and asylums, but he devoted most of his efforts to developing a design for a Panopticon prison, and it is his prison which is most widely meant by the term.
Bentham himself described the Panopticon as "a new mode of obtaining power of mind over mind, in a quantity hitherto without example."Elsewhere, in a letter, he described the Panopticon prison as "a mill for grinding rogues honest".