Digital (or as it is more popularly known,
electronic) ink combines the strengths of
paper with the strengths of
electronic displays, while reducing, and in some cases eliminating, their respective weaknesses.
Paper is easy to read, inexpensive, and malleable-- but static. Electronic displays, on the other hand, can change their content as needed. Currently, however, electronic display technology is hard on the eyes, and flat-panel displays are fragile, expensive, and consume large amounts of power.
E-ink is made up of very tiny microcapsules filled with negatively charged pigment chips suspended in a liquid. The ink is sandwiched between thin, flexible electrodes. When the top electrode has a positive charge, the pigment chips are attracted to the top of each microcapsule, making them appear lighter by reflecting ambient light. When the charge is reversed, the chips are repelled, making the capsules look dark.
The text created requires power only when the display changes. This is called bi-stable behavior, and means that e-ink-based displays draw very little power compared to other display technologies, which must be constantly refreshed to maintain their image.