Amazon is clamping down on the types of content that can be sold on its Kindle platform by authors and publishers.
In a note posted on its Kindle Direct Publishing forum, Amazon said it that it would no longer "accept content that is freely available on the web unless you are the copyright owner of that content".
Amazon said it would continue to accept public domain content, but said it may not allow it to be sold if "its content is undifferentiated or barely differentiated from one or more other books".
The moves may reduce the amount of so-called junk content self-published on the Kindle platform, much of its derived from public sources with no obvious copyright owner. But it could also hit those publishers who legitimately publish public domain, or out of copyright texts. It is not clear how Amazon defines "undifferentiated or barely differentiated" works.
Amazon also said that it would not accept books that provide "a poor customer experience", adding: "Examples include poorly formatted books and books with misleading titles, cover art or product descriptions."