Libraries have a unique role as a bridge between users and information containers. Currently, information containers usually consist of books, journals and electronic files. While the format of information containers changes over the years, the library’s role stays the same. As digital libraries proliferate, the classical library has a new role as information producer. In this paper, we discuss the EPUB format, developed by the International Digital Publishing Forum (IDPF) as an open standard for e-books, and its use as a new information container format in libraries and digital libraries. Several different formats (e.g., .doc, .odf, .txt, .html, .DjVu) are used in digital libraries, but the EPUB format stands out as it has open file structure and is easy to produce and use. Because of its ease of use, mobile devices and e-book readers such as Kindle immediately started to support it. As EPUB is an open and free format, it enables publishers and digital libraries to publish license-free e-books. We review the EPUB format in this paper and show how to produce an EPUB file along with its use with digital library applications such as DSpace, EPrints and Greenstone.