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The EPUB format is a standard eBook format recommended by The International Digital Publishing Forum. It is essentially a ZIP format. If you change its extension ".epub" to ".zip", the EPUB file becomes a true ZIP file which can be unzipped. Format SpecificationsThe unzipped EPUB files may be divided into three categories: XHTML documents, packaging files and container files. XHTML Documents. XHTML is a strict version of HTML. The stricter syntax enables web browsers or eBook viewers to render the document more easily. This is important for reading eBooks on devices with limited computing power such as cell phones. In an EPUB book, the main content is placed in these XHTML documents, which can have .html, .xhtml or .xml extension. We prefer the .html extension because it can be viewed by most web browsers on various computing devices. Our WEB books use exactly the same XHTML documents as in our EPUB books. Packaging Files. They include two files: one with the .opf extension and another with the .ncx extension. The .opf file contains book information (author, publisher, etc.) and a list of all files in the book package. The .ncx file tells the sequence and organization (parts, chapters or sections) of XHTML documents in a book. Container Files. They must be placed in a folder named "META-INF". These files are used for encryption and digital rights management (DRM). For an eBook without DRM, the container file has only a few standard lines. EPUB ViewersCurrently, the EPUB format can be viewed by Calibre, Adobe Digital Editions (ADE), Stanza, Aldiko and a few others. Calibre renders CSS and table of contents very well, but it cannot highlight or annotate. ADE has the highlighting and annotation features. However, scrolling is not smooth when there are images or tables. Another problem is that the table cannot be centered and content may be lost for a long table. For instance, our Complete Poems by E. A. Poe can be displayed perfectly by Calibre, but a lot of contents are missing by ADE. Both ADE and Calibre do not run on any smartphone yet. ADE requires Flash Player which will be available on most smartphones soon (News). At present, you may use Stanza to read EPUB books on iPhones or Aldiko on Android-operated devices. Creating EPUB BooksA number of software tools are designed for making EPUB books, such as Adobe's InDesign or Calibre. Our web-based platform can help you convert Word to EPUB. It also includes an XHTML editor for revising converted documents. The XHTML editor is as easy to use as a regular word processor. You can even use the editor to write a book from the beginning. Free EPUB BooksGoogle has 500,000 public domain titles in the EPUB format. These EPUB books were scanned from print books without spelling check. ManyBooks has 25,000 EPUB books which were converted from text-only version (without images). The EPUB books at Project Gutenberg include images, but their table of contents are incorrect. Our EPUB books include images and have correct hierarchical table of contents. Although our collection (~ 1300 titles) is relatively small, but it is growing. These eBooks are not limited to old books. Many of them will be compiled and edited from contemporary sources which are either in the public domain (e.g., from U.S. National Institute of Health) or released under the Creative Commons license (e.g., from Wikipedia). Some of them are original works submited by users like you.
Frank Lee |