e-reader

An e-reader, also called an e-book reader or e-book device, is a mobile electronic device that is designed primarily for the purpose of reading digital e-books and periodicals.

Any device that can display text on a screen may act as an e-reader, but specialized e-reader devices may optimize portability, readability (especially in sunlight), and battery life for this purpose. A single e-reader is capable of holding the digital equivalent of hundreds of printed texts with no added bulk or measurable mass.