<human>: Which is more popular, a Kindle or a Nook?
<bot>: A Kindle is more popular than a Nook. The Kindle is an e-reader that uses electronic ink technology to display text and images. The Nook is an e-reader that uses E Ink technology to display text and images. Electronic ink displays are generally considered better for reading books because they have higher contrast ratios and are easier on the eyes.