Analog: Any continuously changing signal that is not restricted to finite set of values. For example, the wave forms of spoken words are an analog signal.

Digital: Data or signals represented by a finite number of values. Analog signals (which can have infinite values) must be converted to digital in order to be computed with.

Circuit: A device that provides a path for an electric current to flow, often modifying that current. In computers, circuits allow for simple logical and mathematical operations using electricity.

Prototype: A first or early model of a product that allows you to test assumptions before developing a final version.