pdf The .pdf file format extension was developed by Adobe systems in 1993 as a means of presenting documents in a consistent manner across different platforms, hardware, operating systems, and applications. The format was not released as an open source document format until 2008, though minimal proprietary technologies still controlled by Adobe Systems exist in the format. Every .pdf document carries with it the necessary meta information required to properly reconstruct the text, fonts, and graphics used to produce the document. This ensures that documents will be viewed in exactly the same way the author intended regardless of the device used to open the document. From conception to date, Adobe Systems has continued to support the format adding features with every iteration of the standard including hardened algorithms for document encryption and privacy. Today, many freely available readers exist allowing you to open and view .pdf documents and create or convert other file formats such as .jpeg and .doc into .pdf documents.
ps The .ps filename extension refers to files authored using the open postscript programming language. The postscript format was developed and first released by Adobe Systems in 1982. It is a dynamically typed object oriented page description language format with graphics primitives that make it appropriate for use in desktop publication workflows. The postscript format quickly became the default language driving high resolution laser printers used by prepress service bureaus because it is well suited to describing page layouts with great precision. Several applications both proprietary and open source can allow you to open postscript files, others such as PDF creator or Adobe distiller will convert the postscript file into a PDF file for viewing. Postscript file editing can also be done with simple text editors given the standard character set used in the language.