Portable Document Format is a file format created by Adobe that preserves formatting integrity across all platforms and may contain text, audio, video, links and form fields. The PDF file format is recognized and maintained by the International Organization for Standardization as an open standard.
PDF files are compressed and must be opened with a reader program such as Adobe Acrobat Reader. PDF file compression makes large documents such as books and manuals downloadable as relatively small files in comparison to the original document's size. A PDF file may be read-only, preventing the reader from editing the original, or writable, allowing the reader to edit it in graphics editing or pre-press software.