Portable Document Format. This is a facility for publishing and downloading documents from the Internet, which preserves exactly the original appearance of the document, and can be viewed by anyone using Adobe Acrobat Reader.

PDF files are especially useful for documents such as magazine articles, product brochures, or flyers in which you want to preserve the original graphic appearance online. A PDF file contains one or more page images, each of which you can zoom in on or out from. You can page forward and backward.