You can start from simple Wikipedia and then download any book on impedance if you are working on research paper you can read any of my paper about impedance aswell as modulus study of resistive component
The impedance spectroscopy is an electrical device characterization technique where one measures the small signal impedance of electrodes, cells and junctions at different biasing and frequency conditions. Therefore it indicates both the static and dynamic behavior of the device.
Normally electrodes and junctions can be described by an equivalent circuits consisting of a parallel combination of a resistance and a capacitor in addition to a series resistance. Therefore it shows mostly a half circle impedance curve.
One normally gets an idea about the conduction across the junctions and interfaces and their speeds.
Such impedance can be measured by a vector impedance meter.
Also device engineer deal with impedance spectroscopy but they speak about the so called signal impedance of the junctions instead of the electrochemical interfaces in electrodes.