It is Amazon balance
Books bought for a Kindle are bought from the Amazon store on the same account, paid from the same balance. So a gift aimed at reading is not locked to reading — if they change their mind it buys a kettle.
Some people consider that a downside for a book-themed present. If you want it to feel like a book gift, say so on the card; the money does not know the difference but the recipient does.
Region is the thing to check
The account's country decides which store the device buys from, and e-book catalogues differ noticeably between markets for rights reasons. A title available in one country may simply not exist in another.
Balance from one country's store will not spend on another's. Confirm which store they use.
Subscription reading
Where the recipient uses a subscription reading service rather than buying titles, balance may or may not pay for it depending on market and billing route. If that subscription is the point of the gift, ask and we will check.
Devices
Balance can usually buy the hardware too, where the store sells it — useful if the gift is meant to get somebody started rather than to stock a library they already have.
Who it suits
Readers who already own an e-reader or read on a phone. For someone who prefers paper, an independent bookshop card lands better — see the books and audio guide.
Asking for one
Country and amount. It is the same product as an Amazon code; we will issue it the same way.