ePaper / eInk is a display technology that mimics the appearance of ink on paper. Unlike conventional displays, ePaper reflects light just like ordinary paper and is capable of holding text and images indefinitely, even without electricity.
The display does not require any power to keep the image and will stay "on" without any power connection for many days before slowly fading. Of course, it is also daylight readable and is very high contrast. This makes it excellent for data-logging applications, outdoor displays, or any other ultra-low power usages.