E-readers like the Amazon Kindle can only do one thing, but they do it very well: they make the reading of digital books as easy on the eyes as the reading of paper books. They have screens that look just like paper, viewable from any angle, viewable even in direct sunlight, and battery life measured in weeks.

If you read ebooks and haven’t switched to E-Ink yet, then you’re seriously missing out.

How do these special screens work? What makes them so much better for reading? How do they manage such impressive battery times? And should you invest in one yourself? Here’s everything you need to know.

E-Ink is a display technology that aims to replicate the appearance of ink printed on paper. As such, the vast majority of these displays are only capable of displaying black and white. Yes, the technology for colored E-Ink has been available for years, but it hasn’t made a way into consumer electronics yet.

The very first device to use an E-Ink display was Sony’s Librie, an e-reader released only in Japan in 2004. It never had widespread adoption, due mainly to its expensive price tag and a file format with heavy DRM that made its ebooks expire in 30 days