Multiterminal elements appearing in circuits identified for systematic mathematical analyses are routinely represented, or modeled, by equivalent subcircuits formed of only interconnected two-terminal elements. The concept of an electrical current is implicit to the definition of an electrical circuit in that a circuit is said to be an array of two-terminal elements that are connected in such a way as to permit the condition of current. The element material and the associated manufacturing methods exploited to realize a particular type of circuit element determine the mathematical nature between the voltage applied across the terminals of the element and the resultant current flowing through the element. A linear circuit contains only linear circuit elements, while a circuit is said to be nonlinear if a least one of its embedded electrical elements is nonlinear. The elements of a circuit are defined electrically by an identifying parameter, such as resistance, capacitance, inductance, and the gain factors associated with dependent voltage or current sources.