As shown on this slide, there are different isolation techniques, starting at the top with galvanic isolation. The definition of this is when isolated circuits that exchange signals without DC current flow between the isolated domains. Transformer isolation is a subset of galvanic isolation, which uses transformers to provide an AC coupled data path with a coil separation providing the isolation. The same topology can also be used to transfer power. Junction isolation is another form of galvanic isolation, typically found in low voltage applications. Instrumentation amplifiers and differential amplifiers comprise the amplifier isolation topology,  which has high levels of common mode signal rejection and maintains and amplifies the signals of interest. Typically, this is low-voltage, in tens of volts, and frequency dependency can be a weakness. Lastly, wireless technology, which has recently been focused mainly on power transmission, but it has also been called the "Holy Grail" of power electronics. Dielectric thickness is variable, and frequency dependencies must be specified per application.