title_body: Can EPUB 3.0 be viewed on EPUB 2 devices This prior question is about the differences between EPUB 2 and EPUB 3.
  
  What is more interesting to me, as an owner of three different EPUB 2 devices, is: can EPUB 3 files, and particularly the book text parts, be rendered on a EPUB 2 reading systems (of course dispensing with EPUB 3 specific features)?
  
  Can all such files be rendered, or do they need special setup? Assuming compatibility is possible, is there software already supporting generation of such EPUB 3 files compatible with EPUB 2 reading systems?
upvoted_answer: The IDPF states the following in a thread about EPUB 3 Rendering in EPUB 2 reading systems
  
  
    Although EPUB 3 is not perfectly backwards compatible with EPUB 2, a goal of the recent revision was to ensure, as much as possible, a basic level of rendering when features overlap.
  
  
  The thread particularly mentions that providing the NCX data is necessary, which has been superseded with EPUB Navigation Documents
  as described in the EPUB 3 changes document
  
  So, if some care is taken, EPUB 3 files can be made to render on EPUB 2 reading systems.