An E-Ink display is a screen designed to look more like printed paper than a glowing monitor. It is commonly used in e-readers, electronic shelf labels, note-taking tablets, and some low-power signs. The display reflects surrounding light, so it can be comfortable to read in bright conditions.
The basic idea is different from an LCD or OLED screen. E-Ink displays use tiny capsules or particles that move when an electric charge is applied. Depending on the charge, dark or light particles appear at the surface, creating text and images. Once the page is drawn, the display can often hold the image with very little power.
That low power use is one of the main benefits. An e-reader can show a page for a long time without constantly refreshing the screen. Power is mostly needed when the page changes. This is why many e-readers can last for weeks on a charge, depending on use and lighting.
E-Ink also has tradeoffs. Refreshing can be slower than a normal tablet screen, video is usually not smooth, and colors may be limited or less vivid. For reading books, menus, labels, and static information, those tradeoffs can be acceptable. For gaming or fast animation, a normal display is usually better.
An easy way to remember it is this: E-Ink is best when the screen behaves like paper. It is built for readability and battery life, not for bright video and rapid motion.