A reader is an electronic device specifically designed for reading books. It looks like a small tablet, but its screen is usually made with e-ink technology. This means that reading from a reader is almost as pleasant as reading from a paper book: the screen does not glare and does not strain the eyes, even if you read for a long time.
Why will a reader become your best friend for reading? First, you can carry an entire library in one device. Imagine having all your favorite books always at hand, and you won't have to carry a heavy bag. Second, readers are usually very energy-efficient — they can last for weeks without recharging. And finally, you can adjust the font size on readers, which is very convenient if you need to enlarge the text a bit.
An example from life: imagine you are going on vacation for a week. Previously, you would have to choose which one or two books to take with you. With a reader, you can take dozens (hundreds/thousands) of books with you — and read whatever you want without limitations.
So, if you love reading and want to always have access to books, a reader is exactly what you need.