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 limitation s 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 microcapsules filled with electrically charged white particles suspended in a colored oil. In early versions, the underlying circuitry controls whether the white particles were at the top of the capsule (so it looked white to the viewer) or at the bottom of the capsule (so the viewer saw the color of the oil). This was essentially a reintroduction of the well-known electrophoretic display technology, but the use of microcapsules allowed the display to be used on flexible plastic sheets instead of glass.

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. E Ink developed a higher performance version of the electrophoretic display, using black and white particles in a clear oil instead of white particles in a colored oil.

There are many approaches to electronic paper, with many companies developing technology in this area. Other technologies being applied to electronic paper include modifications of liquid crystal displays, electrochromic display s, and the electronic equivalent of an Etch-A-Sketch at Kyushu Univerisity. One form or another of electronic paper is being developed by Gyricon (which was spun out of Xerox), Philips Electronics, Kent Displays, Nterra, and many others. One important feature needed is that the pixels be bistable so that the state of each pixel can be maintained without a constant supply of power.

In April, 2004, Sony announced the first commercially available electronic paper device, the LIBRIé.