Technical Abstract: This presentation is the Introduction to the Symposium on Feeding Processes and Their Role in Hopper-Plant-Microbe Interactions. The purpose of this talk is to provide basic information on the principles and applications of EPG. This will provide sufficient background for the audience to understand and appreciate the results to be presented in several of the papers in the Symposium. The basic principle of EPG is simple. An output wire from the monitor into the soil of a potted plant electrifies the plant with a low-voltage AC or DC signal. A very thin, gold wire is glued to the dorsum of a test insect using silver conductive paint. The tethered insect is then connected to the input of the monitor, and placed on the electrified test plant. When the insects inserts it stylets into the plant (to begin stylet penetration, also called probing), the circuit is closed and current flows through the stylets, the insect and into the monitor. The voltage of that signal is then measured across the input resistor of the monitor, which provides an accurate model of the voltage of the plant-insect interface. Feeding behaviors of the insect cause variable resistance to the applied signal. This changes the constant applied voltage into a variable voltage that, when collected over time, produces a waveform.