PDF is a file format developed by Adobe Systems for representing documents in a manner that is separate from the original operating system, application or hardware from where it was originally created. A PDF file can be any length, contain any number of fonts and images and is designed to enable the creation and transfer of printer-ready output.
Each PDF file encapsulates a complete description of a 2D document (and, with the advent of Acrobat 3D, embedded 3D documents) that includes the text, fonts, images and 2D vector graphics that compose the document. They do not encode information that is specific to the application software, hardware, or operating system used to create or view the document.
The ePUB file type is an open source format developed by the International Digital Publishing Forum (IDPF) . Based on XHTML, XML and CSS it works well with a number of software applications which has helped the popularity of the format grow. Despite this, there are a raft of rules that must be adhered to when creating an ePUB file which has attracted criticism of the format. The format allows DRM protection to be added to a file.
The ePUB format allows reflowable content. This means that the content fits the size and shape of the screen it is being displayed upon, in the same way that text on an HTML page changes depending on the size of the display. An ePUB file tends to consist of three elements: archive, metadata and content.
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