Portable Document Format (PDF)

A file format designed to hold fixed format documents.

The main advantage of PDF as an e-book format is that it can be read on a wide variety of devices, including almost all personal computers, and many older devices that predate the popularity of EPUB.

PDF's are also used as printing press master files (for example, for print-on-demand books), and for government and business documents that need to be sent via e-mail or printed and filled out.

PDF was developed by Adobe Inc.