All conductors have resistance and the amount of resistance varies with the element. In general, metals make the best conductors of electricity and non-metals make the worst conductors of electricity.

Capacitors store electricity and are used in circuits as temporary batteries. Capacitors are charged by DC current (AC current passes through a capacitor) and that stored charge can later be dissipated into the circuit as needed. Capacitors are often used to maintain power within a system when it is disconnected from its primary power source or to smooth out or filter voltage within a circuit.

Resistors can be chosen in a wide variety of values to control the voltage in a circuit, limit the current, or moderate the heat produced by the components in the circuit.

Current is the rate of flow of electrons per unit time and is measured in amperes (A). An ammeter is used to measure the electric current in a circuit.

A semiconductor is a material that has a limited ability to conduct electrical current with conductivity between that of an insulator and that of a conductor. Silicon, a cheap and abundant material, is the most used semiconductor material although other materials are used in the electronics components made from semiconductors. The primary advantages of a semiconductor over a conductor is that the conductivity of a semiconductor can be varied under an external electrical field giving engineers precise control over complex circuits and, unlike conductors like metals, a semiconductor's conductivity increases with increased temperatures.