Electronic paper is a screen medium designed to look and behave somewhat like a physical page. The best-known form is e-ink, which uses very little power and can keep an image visible even when the device is idle or unpowered. That makes it useful for e-readers, badges, labels, and signs where a paper-like display is easier to read than a bright LCD.
In cyber security, electronic paper matters because it is still a digital display, not printed ink. Anything shown on it can be changed by the software and network path that delivers the content. If that path is compromised, an attacker could alter a label, QR code, warning, or access instruction to mislead users. Defenses focus on secure firmware, authenticated content updates, and physical control of the device, since the display itself is only as trustworthy as the system feeding it.