Prime Reading is a part of Amazon Prime where readers can access thousands of ebooks for free.
Amazon.fr added a Prime reading feature to Amazon Prime this week. Subscribers can now access thousands of ebooks, all for free. It's hard to tell the exact figure (that is shown only to paying customers) but I am told that Harry Potter books are included, and so are Anna Gavalda.
The service is free to readers, but authors and publishers are paid a flat fee for putting their works in Prime Reading for a set period of time. The payment and period varies based on a book's popularity, with Amazon paying anywhere from 100 euros to a couple thousand dollars for the rights to include a book in Prime Reading for a period of 180 days. (The book will of course remain in the regular Kindle Store during that time.)