 Electrical impedance spectroscopy, EIS, is a powerful technique for investigating the electrical properties of various materials. It can be used to quickly characterize solids, liquids, semi-liquids, organic, and inorganic materials. The technique involves applying a sinusoidal voltage or current to the material under test and measuring its impedance over a specified frequency range. The resulting data can then be used to determine the material's electrical properties and behavior. EIS has been widely adopted in many applications such as quality control, process monitoring, and failure analysis. This article was authored by Mgrosi and Biriko.