The notation $$\frac{d^n y}{dx^n}$$ represents the nth derivative of a function y with respect to the variable x. This notation is crucial in understanding how a function behaves as you take successive derivatives, which provides insights into its curvature and rate of change. In particular, this term is foundational in analyzing differential equations, such as Cauchy-Euler equations, where these derivatives are used to form characteristic equations that help find solutions.