This document explains what PDF files are and how to view them.
PDF (Portable Document Format) is a file format developed by Adobe Systems as a means of distributing compact, platform-independent documents. PDF documents are superficially similar to HTML; a PDF document may contain images and text, as well as hyperlinks. However, as PDF is based on a variant of PostScript, each document is completely self-contained--packing text, graphics, and fonts into a single file. Because PDF documents are World Wide Web accessible--yet display and print exactly as intended--print publishers often favor PDF over HTML.
PDF files can be viewed with the Adobe Acrobat Reader or the Acrobat Reader Web-browser Plug-in, both of which can be downloaded for free from Adobe. PDF files can be created with the full version of Adobe Acrobat.