ePub is a popular format for electronic books. Just like the mobipocket format (used for Kindle books), ePub is a container for HTML and CSS. For this reason, you’d think that reading ePub books on any platform would be as easy as opening a web page.
Sadly, this isn’t the case. On any platform, it’s easy to find an ePub reader, but you won’t necessarily get a good one. An ePub is much easier to read if the reader renders sharp text without distractions, and lets you change the font size and padding.
My favourites for each major platform: