Define the term "Impedance".

The unit for electrical impedance is an ohm.
Resistors reduce the flow of current through a wire/metal. In a DC circuit, they steadily resist the same amount of current, regardless of power source frequency. In an AC circuit, new variables like the particular frequency of the AC current can impact resistance. To function properly, components like capacitors and inductors must react to changes in current and frequency.
Inductors and capacitors in an AC circuit not only resist current, but also have the ability to store and release energy. While a resistor will hold a constant resistance regardless of changing conditions, inductors and capacitors will change their resistance based on the signal frequency. A measure of impedance occurs when inductors/capacitors are both storing/releasing energy and resisting current.
Electrical impedance provides a form of resistance to a current, based on the operating frequency of the circuit.