Adobe PDF

The Portable Document Format was invented by Adobe Systems, and first released in 1993. The format was developed to provide a platform-independent means of exchanging fixed-layout documents. Because PDF documents can easily be viewed and printed by users on a variety of computer platforms, they are very common on the World Wide Web and in document management systems worldwide.

Because the format is designed to reproduce fixed-layout pages, re-flowing text to fit mobile device and e-book reader screens has traditionally been problematic.

Third party viewers such as xpdf and Nitro PDF are also available. Mac OS X has built-in PDF support, both for creation as part of the printing system and for display using the built-in Preview application.

PDF files are supported by almost all modern e-book readers, tablets and smartphones. However, PDF reflow based on Tagged PDF, as opposed to re-flow based on the actual sequence of objects in the content-stream, is not yet commonly supported on mobile devices. Such Re-flow options as may exist are usually found under “view” options, and may be called “word-wrap”.