 The hype. It was over for the last two years. But get this. The Kindle is making a comeback. Rediscovered by Gen Zers on TikTok. More precisely, by the Gen Zers of BookTok. TikTok's literary subculture. Kindle sales grow each year by double-digit percentages. Why? After all is said and done, print books are still the most popular. But with e-books, digital borrowing is hot. Much of it is powered by Kindle Unlimited. That's Amazon's $12 a month subscription service.