Electronic paper, or e-paper, is a technology that allows the text on a piece of paper to be re-written. The "paper" is actually made of organic electronics that use conductive plastic which contains tiny balls that respond to an electric charge, changing the page in much the same way that pixels change on a computer monitor.
Electronic paper was developed in order to overcome some of the limitations of computer monitors. For example, the backlighting of monitors is hard on the human eye, whereas electronic paper reflects light just like normal paper. It is easier to read at an angle than flat screen monitors. Because it is made of plastic, electronic paper has the potential to be flexible. It is light and potentially inexpensive.
Electronic paper was first developed in the 1970s by Nick Sheridon at Xerox's Palo Alto Research Center. The first electronic paper, called Gyricon, consisted of tiny, statically charged balls that were black on one side and white on the other. The "text" of the paper was altered by the presence of an electric field, which turned the balls up or down.
In the 1990s another type of electronic paper was invented by Joseph Jacobson. This used tiny balls filled with electrically charged white particles suspended in oil. The underlying circuitry controls whether each ball turns white side up or dark side up.
Jacobson formed E Ink in 1997 to develop electronic paper commercially. The first commercial use occurred in 1999, an in-store display at a department store that featured a changing message. In addition to E Ink, electronic paper is being developed by Gyricon (which was spun out of Xerox), 3M, IBM, and Lucent Technologies.