Portable Document Format (for Archiving)
Stricter form of PDF which is guaranteed to be self-contained.
|types||Image, Text (formatted)|
|related formats||DOC, DOCX, GIF, JPEG, ODT, PDF, PNG, PostScript, SVG, TIFF|
PDF has been developed by software maker Adobe to represent printed documents faithfully and consistently independent of the computer and platform where it is displayed.
It has a subtype called PDF/A which is specifically designed for long-term sustainability. PDF/A is the international standard for Text (formatted) documents. A PDF/A file is a stand-alone document: all fonts and images are included in the file, so it is not dependent on other files on the computer to correctly display its content. No part of the contents of a PDF/A file is encrypted.
There are several types of PDF/A. PDF/A-1a is recommended for text documents that were created entirely on a computer (“born digital”). For digitized documents PDF/A-1b is a suitable format.
PDF viewers are pretty much part of the operating system nowadays, but if not, the Adobe Reader can be downloaded for free.
Facilities to create PDF are near universal, because either the operating system or many applications let you "print" files as PDF. For example, Microsoft Word. Excel, and Powerpoint let you export documents as PDF, and so do the open source office suites such as LibreOffice and the Mac programs Pages, Numbers and KeyNote.
It is also possible to generate PDF as output from programs, there are good libraries to create custom PDFs.
Modifying PDF files is less well supported by free programs, although marking up PDFs with annotations is getting mainstream.