Epubs are books that can be read on a digital device (such as an e-reader, a tablet, or a modern cellphone). Unlike PDFs, the text in an epub flows to fit the screen a person is reading on.
PDFs often look very much the same as printed publication and will have the same number of pages. Epubs do not look much like their printed counterparts and the page count changes - it depends on the size of the text, which is controlled by the person reading the electronic book.
Not all e-readers can read epub files. Kindle devices, for example, read a different format of electronic book. However, the software required to read epubs is increasingly included on modern cellphones. For more information about epubs, see wikipedia.org/wiki/EPUB.
Over time, we will be providing more epub versions of the publications on our site. If a publication is available as an epub, you'll see it listed along with the PDF.
Page last updated: 24 June 2015