the kindle does not stipulate that you must use a credit card, and there is no clear regulation.

Kindle e-books and tablets are relatively cheap, because Amazon mainly relies on the sales of content (such as kindleebook). Amazon advocates long-term profit, rather than relying on hardware to win revenue, and has carried out many innovations in products and business models. Extended information

Amazon Amazon is the world's largest online bookstore. In addition to its rich resources, the main feature of Kindle's competitiveness is its network support function, including Wi-Fi and 4G. Among them, 3G network is CDMAEV-DO wireless network cooperated by Amazon and Sprint, unlike Wi-Fi, which needs external network support.

Amazon provides more than 9, kinds of e-books for users to download, most of which cost $9.99. Besides, Amazon can subscribe to newspapers and magazines, such as new york Times, The Wall Street Journal, Washington Post and Time Magazine, Forbes, etc., and even subscribe to blog, but there is a charge.

Baidu encyclopedia -Kindle