With the adoption of EPUB as the industrie standard for eBooks we’re now seeing many pubilshers developing their content in this format. Almost all systems can currently read EPUB books (excluding the Amazon Kindle — though conversion tools are available) as this ebook format is built on many web standards (XML, HTML, CSS), which are then packaged up in a ZIP file archive.

So far, EPUB hasn’t been used much for textbooks, however, as more reading system being developed we’re seeing many publishers and authors adopting it as one of their formats. Over time it’s expected textbooks will become available as ebooks and thus as EPUB.