Not sure which eBook version to download? Here are some handy descriptions of each file type so you can chose which one best suits you!
The PDF (Portable Document Format) is the most universal file type which most devices can read, however it's a set format, meaning you can't adjust the font/text size/page colours etc. This version is really the default, but is also recommended for those on devices with larger screens such as computers or tablets.
The EPUB (Electronic Publication) is a more flexible eBook format where the text can adapt to various apps and mobile devices, allowing you to change the font, text size and page colours, among other things. This version is recommended for those on small mobile devices such as smart phones and/or those who find screen reading more difficult. Bear in mind that you will need an appropriate browser plugin or application to open this file type like Apple Books (for Apple products) or Freda (for Windows).
MOBI is the file type favoured by Kindle devices. Much like EPUBs, it's a very versatile and adaptable format. This version is recommended for those using eReaders such as Kindles or Nooks, however they can also be read on other devices through the Kindle App.