The dependence of the rotation number on parameters in families of circle diffeomorphisms–often visualized as a “Devil’s Staircase”–is a fundamental object of study in one-dimensional dynamics. While the monotonicity and continuity of the rotation number is well-established, its regularity properties are more subtle. In this talk, we present Jacek Graczyk’s proof (1991) that for any C^2 one-parameter family of circle diffeomorphisms that also satisfy some other natural assumptions, the rotation number is Hölder continuous with exponent equal to ½. We will derive this result by first organizing frequency locking intervals according to the Farey tree, then establishing the universality of “harmonic scaling” in the parameter space with the help of this organization.