EPUB, which stands for electronic publication, is a open file format. By publication, we usually mean digital books (ebooks), but it can more generically mean anything you’ve already seen represented as a PDF file.
EPUB is based on Web Standards: it defines a means of representing, packaging and encoding structured and semantically enhanced Web content — including HTML, CSS, SVG, images, and other resources — for distribution in a single-file format.
In practice, an EPUB file is a zip archive which contains XML structures, HTML and CSS resources, images and – with EPUB 3 – javascript code, audio and video assets.
Using open Web Standards in EPUB brings many advantages to the publishing industry:
- By essence, Web Standards are interoperable, meaning they aim at being usable on any kind of device; so is the EPUB standard.
- Developers of the EPUB specification benefit from the work of the entire Web community. As an example, ebooks accessibility is leveraged by the work done by the W3C on the subject.
- Developers of EPUB authoring solutions can create such tools as variants of Web authoring solutions.
- Developers of reading applications can use as core for their rendering engine an off-the-shelves Web browser engine.