# EPUB

> Source: https://www.infinitelibrary.ai/glossary/epub

Last updated: 2026-09-06
Category: Audio, ebook & formats
Also called: Electronic publication · EPUB 3

EPUB is the open ebook standard — a ZIP of XHTML and CSS that reflows to any screen — accepted by Apple Books, Kobo, Google Play and Amazon KDP alike.

## Definition

**EPUB** (electronic publication) is the ebook format nearly every store and reading app understands. Technically it is a ZIP archive containing the book's text as **XHTML** files, a stylesheet, images, fonts if any, and a manifest (the *OPF* package) that lists the reading order and metadata. Because the text is HTML, it **reflows**: the reader chooses the type size and the pages rearrange themselves.

The standard began at the IDPF in 2007 and is now maintained by the W3C. **EPUB 3** (2011 onward) adds HTML5, audio and video, MathML, accessibility metadata and an optional **fixed-layout** mode for picture books and comics.

Apple Books, Kobo, Google Play Books and most library systems take EPUB directly. Amazon Kindle no longer has its own upload format in practice: KDP accepts EPUB and converts it to Kindle's internal formats. A validated EPUB (via EPUBCheck) is therefore the one file that reaches every ebook shelf.

## In Bindery

Bindery Pro includes a clean EPUB alongside the print-ready PDF for every book, and each published book’s free storefront sells the ebook at about 95% royalty.

## Related

- [Reflowable vs fixed layout](https://www.infinitelibrary.ai/glossary/reflowable-vs-fixed-layout)
- [Print-ready PDF (PDF/X)](https://www.infinitelibrary.ai/glossary/print-ready-pdf)
- [Storefront (author storefront)](https://www.infinitelibrary.ai/glossary/storefront)
- [Royalty](https://www.infinitelibrary.ai/glossary/royalty)
- [Turn a PDF Into an Ebook](https://www.infinitelibrary.ai/tools/pdf-to-ebook)
- [Turn an EPUB Into a Printed Book](https://www.infinitelibrary.ai/tools/epub-to-printed-book)
- [Book Publishing Glossary — 59 Terms Defined](https://www.infinitelibrary.ai/glossary)
- [Bindery — the Claude-powered book studio](https://www.infinitelibrary.ai/bindery)

---

More from Infinite Library, as one map for AI agents: https://www.infinitelibrary.ai/llms.txt