EPUB

EPUB is an open standard file format for digital publications, especially e-books.

EPUB is an open standard file format for digital publications, especially e-books. Its name is short for electronic publication, and files typically use the .epub extension. EPUB is designed for reflowable content, so text can adapt to different screen sizes and devices.

History

EPUB was developed as an open e-book standard by the International Digital Publishing Forum and became an official IDPF standard in 2007. EPUB 3 later extended the format for richer web-based publication features and was standardized in the broader EPUB 3 ecosystem.

File structure

An EPUB file is a compressed ZIP archive containing structured publication resources. These usually include XHTML or HTML content, CSS stylesheets, images, fonts, navigation files, and metadata.

Use and compatibility

EPUB is widely used for e-books and other digital publications because it works across many devices and apps. Its reflowable layout makes it especially suitable for varied screen sizes, unlike fixed-layout formats.

Standards and governance

EPUB was originally defined by the IDPF, which later became part of the W3C EPUB 3 Community Group structure. EPUB 3 is also identified as an ISO standard.