The Overton window is a theory that suggests there is a range of ideas the public will accept. The window is named after Joseph P. Overton, who developed the theory while working as a vice president at the Mackinac Center for Public Policy. The range of ideas is based on what is considered politically acceptable at the time. The window can move over time as public opinion changes. The theory is used by activists to gauge where the public stands on an issue and to determine what ideas they should promote to move the window in their favor.