What is a PDF?

 What is a PDF?
Portable Document Format (PDF) is the de facto standard for the secure and reliable distribution and exchange of electronic documents and forms around the world, with a ten-year track record. PDF is a universal file format that preserves the fonts, images, graphics, and layout of any source document, regardless of the application and platform used to create it.

Adobe® PDF files are compact and complete, and can be shared, viewed, and printed by anyone with free Adobe Reader® software. To date, more than 500 million copies of the software have been distributed. You can convert any document to Adobe PDF using Adobe Acrobat® software products, enabling business, engineering, and creative professionals to create, distribute, and exchange secure and reliable Adobe PDF documents. 

What is Adobe Reader?
Adobe® Reader® 7.0 is free software that lets you view and print Adobe Portable Document Format (PDF) files on a variety of hardware and operating system platforms.