Electrophoretic technology refers to the process whereby thousands of microcapsules, containing (negatively charged) black and (positively charged) white pigments suspended in a clear fluid, are encapsulated in a plastic sheet.
When a charge (positive or negative) is applied, the corresponding particles move to the top of the microcapsule and the surface appears black or white in this specific area. When the charge is removed, the particles stay where they are. This is called bi-stability: where something can rest in either of two states.
In the case of an EPD, the text and/or images remain on the screen until the next update and the user can continue to view the content without the need for battery power. This means EPDs are inherently low-power and is one of the main differentiators to conventional backlit flat panel displays, where a constant power supply is required to maintain content.