The Overton window is a political theory that describes the range of ideas the public will accept as a narrow "window". According to the theory, an idea's political viability depends mainly on whether it falls within that window rather than on politicians' individual preferences. It is named for its originator, Joseph P. Overton (1960–2003), a former vice president of the Mackinac Center for Public Policy. At any given moment, the "window" includes a range of policies considered politically acceptable in the current climate of public opinion, which a politician can recommend without being considered too extreme to gain or keep public office.
Overton described a spectrum from "more free" to "less free" with regard to government intervention, oriented vertically on an axis. As the spectrum moves or expands, an idea at a given location may become more or less politically acceptable. His degrees of acceptance of public ideas are roughly: