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PDF

PDF (Portable Document Format) is an open standard developed by Adobe intended to preserve documents in a manner that allows them to appear identical on every device on which they are viewed.

PDF documents are not reflowable, and are limited to a fixed page size. While some readers will attempt to reflow them anyway, this can often have undesired results.

PDF should generally be used only as a last resort on devices which are capable of reading EPUB or Mobipocket files.