E-Ink is a type of electronic paper manufactured by E Ink Corporation. It can be applied to the same materials that regular ink can be printed on. Take a digital book for instance. Here the pages would be made out of some kind of ultra-thin plastic. The ink would cover the entire page, separated by cells that resemble the cells on graph paper. Think of these cells as pixels on your computer screen, with each cell wired to microelectronics embedded in this plastic sheet. These microelectronics would then be used to apply a positive or negative charge to the microcapsules to create the desired text or images. Remarkable.

It's worth noting that e-ink is yet another in a growing list of inventions which seek to imitate real-world ones. The great paradox is that as we become ever more immersed in the virtual world, we are finding more and more ways to replicate that which is real.