I've been fascinated by single-purpose devices such as iPods for music, flip-phones for communication, and e-readers for ebooks. Considering that my interest for these devices has reached an all-time high, I was wondering: **Why has the iPod died out while e-readers continue to thrive and see growth?** Don't they both serve the same purpose of allowing users to enjoy one (primary) form of entertainment? Aren't both types of devices easily replaceable by a modern smartphone or tablet today?