In July 2014, Amazon added the Kindle Unlimited subscription service that initially offered unlimited access to over 638,000 titles and over 7,000 audiobooks for a $9.99 monthly fee. The library was later expanded to include Fire tablets as of February 2018, the service had over 1.7 million titles available.

This perk allows access to the 'Kindle Owners' Lending Library' where users can borrow one e-book, choosing from over 600,000 titles as of July 2014, per calendar month from the Kindle Store for free. The Lending Library was added in late 2011 for Amazon Prime members with Kindle e-readers. The service debuted with the Kindle 2's release in February 2009. Whispersync is a service provided for e-books acquired from the Kindle Store that allows customers to synchronize reading progress, bookmarks, and other information across Kindle devices and Kindle apps. The Kindle Store uses a recommendation engine that looks at purchase history, browsing history, and reading activity, and then suggests material it thinks the user will like. One of the innovations Amazon brought to the store was one-click purchasing that allowed users to quickly purchase an e-book. Content from the store is purchased online and downloaded using either Wi-Fi or Amazon's Whispernet to bring the content to the user's device. As of March 2018 there are over six million titles available in the U.S. In July 2014, there were over 2.7 million titles available. This number increased to more than 275,000 by late 2008, and exceeded 765,000 by August 2011. At the launch of the Kindle in November 2007, the store had more than 88,000 digital titles available in the U.S. The Kindle Store is an online e-book e-commerce store operated by Amazon as part of its retail website and can be accessed from any Amazon Kindle, Fire tablet or Kindle mobile app. The New Yorker digital subscription via the Kindle Store

Amazon online library books