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Definition: PDF


(Portable Document Format) The de facto standard for electronic document publishing from Adobe. Introduced in 1993, today there are billions of brochures, data sheets, white papers, forms and technical manuals on the Web in the PDF format.

Render, Save As and Edit
Adobe's free Acrobat Reader and many other applications can display and print PDF files. Countless programs can save documents to PDF; however, changing the content in the file requires Adobe Acrobat or other software that features PDF editing.

Why PDFs Are So Popular
The PDF format solves the font copyright and patent problem and enables document creators to use whichever fonts they have at their disposal. Prior to PDFs, documents relied on the installed fonts in the computer. If a document was created using fonts C and E, but it was sent to a computer that lacked one or both of the fonts, the document would display and print incorrectly. However, with PDFs, document creators can use whichever fonts they have because the rules for rendering the fonts are embedded within the PDF file itself. See PDF/X and font incompatibility.

Non-Searchable Text
Most of the time, text within a PDF document can be searched as well as copied to another file. For copyright protection, PDFs can be saved as an image, which makes the text non-searchable and cumbersome to copy. However, PDF programs may offer an optical character recognition (OCR) feature that creates a text layer from the images, and that text can be searched.

PDF Is a Superset of Adobe PostScript
PDF is the preferred file format for sending documents to commercial print houses. If the commercial printer uses PDF imagesetters, no conversion is necessary. If it uses only PostScript hardware, the PDF files are converted to PostScript first. See PostScript, PDF/A, PDF/X, WWF, DjVu and XML Paper Specification.




PDFs Are Size Efficient
Compare the sizes of this PDF file with its JPEG and Microsoft Word (.doc and .docx) equivalents. These are all the same single-page text documents saved to four formats. Whereas the PDF and Word formats are aware of the file's contents, the JPEG image is always a matrix of pixels (see JPEG and DOC file).