An open eBook standard created by the International Digital Publishing Forum (IDPF). Features reflowable text, inline images, and supports DRM (Digital Rights Management) protected eBooks, similiar to ADE (Adobe Digital Editions)
A format primarily designed for PDAs and smart phones. Allows access to DRM and non-DRM content. Epub format can also be converted easily into mobi format.
PDF, or Portable Document format, was created in the early 90s as a document sharing format. It is best for highly formatted content, images, and has the ability to support DRM (Digital Rights Management) content.