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EPUB (Electronic Publication) | Future Of Publishing

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EPUB (Electronic Publication) emerges as a prevalent open-standard file format catering to digital literature, documents, and various publications. Its reflowable nature denotes adaptability to diverse screen dimensions, orientations, and resolutions autonomously. Consequently, e-books employing this format seamlessly traverse an array of devices, encompassing e-readers, smartphones, tablets, and computers.

These files bear the .epub extension and fundamentally comprise a compendium of HTML, CSS, and multimedia files (including imagery, audio, or video), meticulously compressed via the ZIP protocol and consolidated into a singular package. This configuration streamlines navigation, affords customizable styling, and accommodates embedded multimedia content.

Despite the allure of the EPUB format, it doesn’t monopolize the domain of digital literature. Alternatives exist, such as online bookmakers, offering the creation of visually striking books replete with interactive features, readily shareable across platforms.

More About EPUB

The EPUB format essentially serves as a container for what can be likened to a digital hub. EPUB files bundle and encrypt upgraded online content for dissemination within a singular package. Each EPUB file encompasses the fundamental framework, HTML documents, CSS formatting sheets, visuals, and any other essentials vital for content presentation.

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By default, EPUB material possesses a flexible layout, ensuring seamless adjustment to the display screen. However, there is also the option to code content for a fixed display. The most recent rendition, EPUB3, aligns with the HTML5 norm and now accommodates multimedia elements like sound, video, and interactive features. Nevertheless, not all e-readers have the capability to showcase such multifaceted content.

In the digital publishing world, the EPUB file format is widely favored for sharing ebooks, magazines, and other written content. It’s supported by most dedicated e-readers like Amazon Kindle, and Kobo, as well as various e-reading apps for smartphones, tablets, and computers.

Structure and Content

These documents serve as compressed archives housing interconnected resources within a single file. Three primary components form the foundational structure of an EPUB archive, all essential for its validity.


The MimeType file, residing at the archive’s root, is a basic ASCII text file declaring the format and processing instructions for the reading system. It simply contains one line: application/epub+zip.


The META-INF folder hosts the e-book’s metadata information, typically featuring a single XML file named container.xml. This file directs the reading application to the location of the ‘package.opf’ file, which provides instructions for processing the e-book’s contents. Additionally, the META-INF directory may contain other documents pertaining to the EPUB, such as embedded fonts and DRM encryptions.

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The OEBPS folder holds the actual contents of the e-book, including text, images, fonts, and stylesheets necessary for on-screen display. This folder comprises three mandatory declarative files: .opf, .ncx, and .css files, alongside all other files constituting the EPUB document.


The .opf file, usually named package.opf or content.opf, is an XML file embodying the structural data. It contains four sections:

1. <metadata>: This section houses meta-information about the Format, such as title, author, cover, synopsis, publication language, publisher, and copyright details.

2. <manifest>: An exhaustive list of all assets comprising the publication, including XHTML chapters, images, fonts, CSS files, and scripts.

3. <spine>: Defines the default reading order of the publication’s chapters, comprised of HTML/XHTML files constituting the actual content.

4. <guide>: Though deprecated in EPUB3, this section points to the e-book’s cover, table of contents, and the actual beginning of the text. Some vendors still utilize it.


The .ncx file, typically named ‘toc.ncx’, is an XML file establishing the navigational table of contents in the e-book, facilitating navigation between elements within the book.


The cascading style sheet (.css) instructs the reading system on formatting specifics, such as font weight, size, colors, page and paragraph margins, ensuring coherent display of information within the publication.

How To View

Apart from the Amazon Kindle app, EPUB files are compatible with the majority of e-book readers available. These readers are accessible across various desktop and mobile platforms, offering both paid and free options.

However, it’s crucial to note that certain EPUB files may be safeguarded using Digital Rights Management (DRM), restricting access to authorized devices or applications only. Typically, e-readers do not support DRM-protected EPUBs originating from other platforms.


Both the PDF and EPUB file formats offer distinct advantages and drawbacks.

PDFs are renowned for their fixed layout, ensuring consistency in formatting and design across different devices and screen sizes. This trait renders PDFs particularly suitable for content necessitating precise presentation, such as technical documents, visually-rich publications like comics, and academic papers.

In contemporary times, PDF has emerged as the standard digital publication format, compatible with numerous internet browsers, and facilitating seamless conversion of diverse documents into PDF format.

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Conversely, this file format retains its popularity, particularly among e-ink devices prized for their energy efficiency and absence of light emission. Leveraging HTML files as its foundation, EPUB remains reflowable and easily adaptable to smaller screens. This characteristic proves advantageous for text-centric content requiring optimal performance on mobile devices.

Create, Edit And Convert

There are three primary methods for creating an EPUB file, each presenting its trade-offs in terms of quality and time investment.

1. Create EPUB from Scratch:

   If you’re proficient in hand-coding website assets like XHTML and CSS files, crafting an e-book from scratch might be the most straightforward and pristine approach. Much like designing a website, you can manually code all necessary assets using a basic text editor or specialized webpage editing software such as Dreamweaver. Applications like Sigil and Calibre offer both WYSIWYG editing and direct code manipulation features.

2. Utilize EPUB Exporting Applications:

   Certain editing applications, either inherently or via plugins, facilitate direct export to EPUB format. For instance, Apache’s OpenOffice, a free office suite, allows users to save manuscripts as e-books using a plugin called Writer2ePub. Commercial solutions tailored for publication preparation, such as Scrivener, Adobe InDesign, and QuarkXpress, also offer robust EPUB creation and editing capabilities.

3. Convert to EPUB Using Software or Online Services:

   Given that many e-books originate as manuscripts in word processing applications like Microsoft Word or OpenOffice, converting files from one format to EPUB using dedicated software or online services may appear convenient. Calibre, for example, supports conversion between various formats like HTML, DOCX, RTF, and MOBI. While free online tools exist for file conversion, post-conversion formatting cleanup is often required.

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Regardless of the chosen method, it’s advisable to validate the final EPUB file using the EpubCheck validator, a free open-source tool. This ensures the EPUB is free of errors within its structural markup, images, and HTML files.


creating an EPUB file offers multiple avenues, each with its own set of considerations. Whether opting to craft from scratch, utilize specialized applications, or convert existing files, it’s essential to weigh factors like familiarity with coding, time constraints, and desired output quality. Regardless of the chosen method, validating the final EPUB using tools like EpubCheck ensures structural integrity and optimal readability. By selecting the most suitable approach based on individual needs and resources, one can effectively produce EPUB files tailored to their intended purpose.

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