What is impedance?

Impedance is the measure of the total opposition that a circuit presents to the flow of alternating current (AC). It acts much like resistance does in a direct current (DC) circuit, but it also accounts for the dynamic effects of capacitance and inductance. Like standard resistance, impedance is measured in ohms. However, because it deals with AC signals, the amount of impedance often changes depending on the frequency of the alternating current passing through the component. The other options describe different concepts: the inverse of resistance is conductance, the Q factor measures a circuit's bandwidth or efficiency, and power handling is simply a component's maximum wattage rating.