Abstract: Techniques for use with electronic book readers include coordinating or translating position information between different versions of an electronic book. Positions within different versions can be translated for various purposes, such as transferring annotations between versions or synchronizing positions within different versions.

Abstract: Techniques for use with electronic book readers include coordinating or translating position information between different versions of an electronic book. Positions within different versions can be translated for various purposes, such as transferring annotations between versions or synchronizing positions within different versions.

Abstract: Architectures and techniques are described to rent electronic books. In particular, a content provider can rent electronic books to individuals for a specified rental term. The individuals may have the option to modify the rental term for an electronic book. The rental term for a particular electronic book may be modified by extending the rental term of the particular electronic book or decreasing the rental term of the particular electronic book. Individuals may also convert the rental of an electronic book to a purchase and a purchase of an electronic book to a rental. In order to rent the electronic books to individuals, the content provider may acquire permission from the publishers of the electronic books. In some cases, the content provider may acquire a pool of time-bound rentable licenses from the publishers to allocate to individuals renting electronic books from the content provider.

Abstract: Techniques for aligning content items with one another are described herein. These techniques may align different versions of a same content item for the purpose of identifying differences between the versions, identifying commonalities between the versions, mapping annotations made in one version to the other version, aggregating annotations across the different versions, or for any other reason. The content items may include electronic books, songs, videos, documents, or the like.

Abstract: Architectures and techniques are described to determine a reading level of an electronic book. In particular, words, phrases, clauses, and parts of speech of an electronic book may be tagged and used to determine the reading level of the electronic book. In some cases, the reading level of the electronic book is based on a level of complexity of sentences of the electronic book and a level of complexity of words of the electronic book.

Abstract: Architectures and techniques are described to rent electronic books. In particular, a content provider can rent electronic books to individuals for a specified rental term. The individuals may have the option to modify the rental term for an electronic book. The rental term for a particular electronic book may be modified by extending the rental term of the particular electronic book or decreasing the rental term of the particular electronic book. Individuals may also convert the rental of an electronic book to a purchase and a purchase of an electronic book to a rental. In order to rent the electronic books to individuals, the content provider may acquire permission from the publishers of the electronic books. In some cases, the content provider may acquire a pool of time-bound rentable licenses from the publishers to allocate to individuals renting electronic books from the content provider.