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.

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:

Unthinkable

Radical

Acceptable

Sensible

Popular

Policy

After Overton's death, others have examined the concept of adjusting the window by the deliberate promotion of ideas outside of it, or "outer fringe" ideas, with the intention of making less fringe ideas acceptable by comparison. The "door-in-the-face" technique of persuasion is similar.