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From PDF City

The Postscript language was created in 1985 by Adobe Inc. to serve as a printing output standard, which soon would be used in most laser printers. Postscript files could contain text, graphics, fonts and other layout elements, such as formatting, orientation and others.

Maybe the most important difference in Postscript from other printing output standards was that postscript image files were portable. That means we could put the printing output into a file and then distribute this file to be printed in any system that had a Postscript printer attached to it.

Other difference was that its contents was pure-text based, so that we could open the file in a text editor and see, copy or change its contents as needs.

By the way, Postscript was not created to be a document file format. In 1990, as the growing of Postscript, Adobe created the Portable Document Format – PDF, this one to be used as a real exchange format. More then printed, it could be used to view documents in screen, with supported facilities, such as zoom, inversion, copy and paste, etc.

As in Postscript files, fonts and images was embedded into the document. Though, visual identity could be maintained through transportation from one platform to other without looses.

In 1993 the Internet was changing for commercial use. Although the HTML format was revolutionary in its compactness and linking capabilities, the browsers and even the HTML itself was limited in visual quality. Changing display setup or Operational System or browser origin and model would produce unpredictable visual impacts. The PDF files, based in a printing image, have, from the beginning, the characteristic of being constant in aspect, which was the most "portable" feature.

But it wouldn't be really portable if interested people didn't have software to open it. Adobe then released Acrobat Reader, as a free downloadable program, so that users could open the documents. Acrobat Reader started to gain functions, in each new version:

• internal links
• links to the Internet
• work in Layers, so that created PDF documents could receive new visual elements
• integration with web browsers, so that PDF files could be viewed in the browser window
• commenting floating elements
• form components
• attachment capabilities
• data exchange capabilities (now-a-days in XML format)
• javascript, with integration with menu commands
• http post protocol, so that documents could interact with Web applications
• pre-flight functionalities

The PDF format definition, initially restricted to Adobe, was published, so that developers could create their own applications and make outputs in PDF format. Today there is a lot of PDF viewers and makers (see the Ghostscript, witch is maybe the most complete and used one).

[edit] City Index

• PDF conversion from other documentos to PDF and vice versa
• PDF forms, standalone and Web forms
• PDF commenting, sending and mailing documents
• PDF signing, verifying and comparing documents
• PDF applications, standalone and Web applications
• PDF repository, attachments, multimedia and dynamic content
• PDF data exchange, importing and exporting data

[edit] References

• Adobe home page
• Planet PDF - reference, forum, products, news and other information
• PDF definition in Wikipedia