What is the Natural Response of a Circuit?

The Natural Response of a Circuit is the response of a circuit which contains an energy storage element(s), a capacitor and/or inductor, with no power source present.

Above is a circuit in which a natural response can be seen. This circuit has two energy storage elements, a capacitor and an inductor. Its natural response can be observed because there is no active device such as a power source present. Therefore, it produces its "natural" response.