E Ink Electronic Paper Display, EPD
Microcapsules with black and white particles moved by electric fields — only draws power when the image changes. Weeks of battery on a Kindle.
Developed at MIT Media Lab in the 1990s, commercialised by E Ink Corporation (Taiwan). Generations: Pearl, Carta, Carta 1200, Carta 1300. Colour variants: Triton (weak colour), Kaleido (filter-based colour, muted), Gallery 3 (more vivid). Powers Kindle, Kobo, reMarkable (writing pads), Boox, historically Pebble smartwatches, labels at Walmart, "smart" signs in the metro. Slow refresh, "ghosting" between pages. No backlight by default — the Kindle Paperwhite has side LEDs.