The method of false position, or Regula Falsi, is based on linear interpolation between two points on a function's curve. It utilizes the concept of a secant line to estimate the root of a function by creating a triangle that represents the area under the curve. This geometric approach allows for successive approximations by adjusting the interval based on the function's behavior. The method is effective for finding roots in cases where the function is continuous and changes sign. Understanding this geometric foundation enhances the application of the method in numerical analysis.