EPUB Format Guide

Available Conversions

About EPUB Format

EPUB (Electronic Publication) is the most widely supported open e-book format, developed by the International Digital Publishing Forum (IDPF) and now maintained by the W3C. It was first released in 2007 as a successor to the Open eBook format and has become the industry standard for digital books, supported by virtually all e-readers except Amazon Kindle (which uses its own formats but can convert from EPUB).

History of EPUB

The EPUB format evolved from the Open eBook Publication Structure (OEBPS) created in 1999. EPUB 2.0 was released in 2007, introducing the standard container format (OCF) and navigation control (NCX). EPUB 3.0, released in 2011, brought major improvements including HTML5 support, CSS3 styling, embedded audio/video, JavaScript interactivity, and enhanced accessibility features. The latest version, EPUB 3.3, was published in 2023 as a W3C Recommendation, ensuring the format's continued evolution and standardization. The merger of IDPF with W3C in 2017 solidified EPUB's position as the premier open standard for digital publishing.

Technical Structure

An EPUB file is a ZIP archive (renamed with .epub extension) containing several components: content documents in XHTML format, a navigation document (replacing the older NCX), CSS stylesheets, images, fonts, and metadata files. The META-INF/container.xml file points to the package document (content.opf), which contains the manifest (list of all files), spine (reading order), and metadata (title, author, ISBN, etc.). EPUB 3 uses HTML5 and supports SVG graphics, MathML equations, embedded fonts, audio, video, and even JavaScript for interactive content. The format supports both reflowable text (adapting to screen size) and fixed-layout pages (for comics, magazines, children's books).

Common Applications

EPUB is the primary format for digital book distribution outside the Amazon ecosystem. It's used by Apple Books, Google Play Books, Kobo, Barnes & Noble Nook, and countless independent bookstores and libraries. Publishers worldwide use EPUB for both consumer e-books and enterprise documentation. The format is popular for self-publishing through platforms like Smashwords, Draft2Digital, and Lulu. Libraries use EPUB with Adobe DRM for digital lending through services like OverDrive and Libby. Educational publishers use EPUB for textbooks with interactive features. The format's open nature and accessibility features make it the preferred choice for organizations focused on digital inclusion.

Advantages and Disadvantages

Why Convert EPUB Files?

• Kindle Compatibility: Convert to MOBI or AZW3 for Amazon Kindle devices
• Universal Reading: Convert to PDF for devices without EPUB support
• Editing Content: Convert to DOCX or ODT to edit in word processors
• Web Publishing: Convert to HTML for online reading and blogs
• Documentation: Convert to Markdown, AsciiDoc, or RST for technical docs
• Academic Publishing: Convert to LaTeX for journals and theses
• Data Extraction: Convert to JSON, XML, or CSV for data processing
• Russian E-readers: Convert to FB2 for PocketBook and other CIS devices
• Archiving: Convert to plain text for long-term preservation
• Presentations: Convert to PPTX for book summaries and lectures

Software That Opens EPUB Files