What PDF is
Portable Document Format (PDF) is an open file format created by Adobe Systems in 1993 and is now being prepared for submission as an ISO standard. It is used for representing two-dimensional documents in a device independent and resolution independent fixed-layout document format. 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.
PDF is primarily the combination of three technologies:
- A sub-set of the PostScript page description programming language, for generating the layout and vector graphics.
- A font-embedding/replacement system to allow fonts to travel with the documents.
- A structured storage system to bundle these elements and any associated content into a single file, with data compression where appropriate.
The PostScript language is the background code describing what is in the document, much like HTML code is the behind-the-scenes code that creates a web page.
A PDF file is often a combination of vector graphics, text, and raster graphics:
- Text stored as such
- Vector graphics for illustrations and designs that consist of shapes and lines
- Raster graphics for photographs and other types of image
The PDF document can also support links (inside document or web page), forms, JavaScript, or any other types of embedded contents that can be handled using plug-ins.
A little known and understood but very important part of the PDF workflow is the printer driver used to output your document file. The printer driver ultimately determines the final code that is placed in the print/save to disk file. It is imperative that you begin your document construction process by choosing a PostScript printer driver (PS abbreviation in the name) rather than a non-PostScript printer driver (often has PCL abbreviation in own name) before you start constructing your document. Windows users should pay special attention to this, because the default printer driver is a non-PostScript printer driver.
For printing on a paper it is also recommended using PostScript printer driver rather the PCL driver with Hewlett-Packard�s page description language when your printer has several versions of printer drivers. The reason for this is that PostScript printer driver produces better, more correct, and smoother PDF hard-copy documents from any PDF files. If you print PDF file through PCL driver, hard-copy will be worse than if you print similar DOC file (from Word editor) through PCL driver, so some users incorrectly suppose that DOC format better than PDF format. It is not true at all! So end-to-end using of PostScript languages becomes increasingly important as the complexity of printing you intend to perform increases.
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