What is E-Ink?
E-Ink is a screen technology, commonly used on portable devices like tablets, that makes you feel like you are reading from a paper.
How it Works
E-Ink displays uses electronic ink as its name suggests. These are pigmented micro-particles inside a capsule. The different pigments carry different charges, so that they can be moved around inside the capsule when an external charge is applied. Common E-Ink displays have black and white pigments with negative and positive charges respectively.
Why it is of Interest
E-Ink uses a fraction of the power used by normal LCD or LED screens and excels in readability even in bright direct sunlight (of course there are dangers of reading in direct sunshine)
Because E-Ink works by actually movement of particles, it is very slow in response and hence is primarily being applied to reading text or viewing still images.