Portable Document Format (PDF) is a file format used to present documents in a manner independent of application software, hardware, and operating systems. Each PDF file encapsulates a complete description of a fixed-layout flat document, including the text, fonts, graphics, and other information needed to display it. In 1991, Adobe Systems co-founder John Warnock outlined a system called "Camelot" that evolved into PDF. While Adobe Systems made the PDF specification available free of charge in 1993, PDF was a proprietary format, controlled by Adobe, until it was officially released as an open standard on July 1, 2008, and published by the International Organization for Standardization as ISO 32000-1:2008, at which time control of the specification passed to an ISO Committee of volunteer industry experts.
FictionBook is a popular XML-based e-book format, supported by free readers such as FBReader, Okular, CoolReader, Bebook and STDU Viewer. The FictionBook format does not specify the appearance of a document; instead, it describes its structure and semantics. All the ebook metadata, such as the author name, title, and publisher, is also present in the ebook file. Hence the format is convenient for automatic processing, indexing, and ebook collection management. This also is convenient to store books in it for later automatic conversion into other formats.