It has become unimaginable to provide information – particularly scientific information – without e‐books. They have become part of today's combination of media, which includes printed books and journals, e‐journals, e‐books, and databases. When e‐books first appeared on the market, librarians very quickly formulated their key requirements. The most important requirement is functionality: it must be possible to look through a book chapter by chapter, and also to get a quick overview of a comprehensive monograph. Usage arrangements, including concurrent usage and use for interlibrary loans, are also important. The use of uniform technical standards increases the acceptance of e‐books.