Taken from the Adobe website
Adobe PDF
More secure, reliable electronic document distribution and exchange
Invented by Adobe Systems and with more than ten years of innovation, Adobe® Portable Document Format (PDF) is a publicly available specification used by standards bodies around the world for more secure, reliable electronic document distribution and exchange. Adobe PDF has been adopted by governments and enterprises to streamline document management, help increase productivity, and reduce reliance on paper. Today, Adobe PDF is a standard, reliable format for the electronic submission of drug approvals to the U.S. Food and Drug Administration (FDA) and for electronic case filing in U.S. federal courts. It is also a standard format used for advertising pages, in newspapers and magazines.
As an open file format specification, PDF is available to anyone who wants to develop tools to create, view, or manage PDF documents. More than 1,800 vendors offer PDF-based solutions.
* Preserve the look and integrity of your original documents — Adobe PDF files look exactly like the original pages and can fulfill requirements for electronic filing and increased document security.
* Share documents with anyone — Anyone using free Adobe Reader® software can open Adobe PDF documents across a wide variety of platforms and devices.
* Easy to use — Adobe PDF files have a wide range of features to enhance usability, color profile information for more accurate color rendition across different systems, as well as tags in the document that reflow the pages for different screen displays.
* More secure document exchange — With Adobe Acrobat® 7.0 or Adobe LiveCycle™ software, you can password-protect PDF files to help prevent unauthorized viewing and altering.
* Searchable — Adobe PDF files are searchable for words appearing in the text and in annotations, bookmarks, and data fields.