title_body: Are there technical advantages of one common format over another?
upvoted_answer: Many of the ebook readers either have or have had their own format. Sony had the LRF format (more properly known as Broadband eBook), for example. Proprietary formats are designed for two reasons:
  
  
  to take advantage of special features of the hardware and software
  to lock users into the vendor's hardware and content ecosystem.
  
  
  Currently, there are at least five commonly used formats that are specifically designed for eBooks (as opposed to PDF which has broader aspirations and use).
  
  
  MOBI (Mobipocket)
  AZW/KF8 (Kindle)
  iBook (Apple)
  LIT (Microsoft)
  ePub (open standard)
  
  
  All of these formats are based on HTML, but with special wrappers, extensions, and/or Digital Rights Management (DRM).
  
  Of the five, ePub is the most open, and therefore preferred by technical consumers who don't like to be locked in to a particular company's hardware and/or software. This has lead most eBook hardware and software vendors to support ePub, as least for books acquired from other sources.
  
  A detailed comparison of eBook formats is available on Wikipedia.