For a short time, anyone who buys an e-book from the Windows Store will get a $5 gift code. Hint: You don’t want the book.
That is, buy the cheapest possible book you can find—99 cents, I think; I chose “Deconstructing Sammy”—and you’re essentially getting a $4.01 Windows Store gift code for free. And yes, you can use that gift code towards any purchase, including apps, games, music, TV shows, or movies.
You can find out more about this promotion from the Microsoft Fire Hose blog.
If you’re curious about the actual e-books for some reason, there are, of course, caveats.
First, no one in their right mind would ever buy e-books from the Windows Store. These books are only usable on Windows 10 PCs, and can only be read in Microsoft Edge. Not exactly ideal reading conditions. (Yes, they work on a handful of Windows 10 Mobile handsets that no uses too.)
You must be running the latest version of Windows 10. Microsoft Edge and the Windows Store gain e-book capabilities with the Creators Update.
You must live in the United States. Even if you are running the Creators Update, the e-book store and reading capabilities only work in the U.S.
This is a limited time offer. You have until June 30 to make your e-book purchase to qualify for this offer.
You must redeem your gift code quickly. You have until August 15 to do so.
Most important, none of this matters. Just enjoy the $4.01 gift card.