PDF: Portable Document Format
PDF (Portable Document Format) is a popular format for storing many types of data including raster images. There are several subtypes of PDF including PDF-A. Additional information about the PDF format can be found at the Sustainability of Digital Formats site at the Library of Congress.
NARA's PDF files version 1.4 and are identified as PUID fmt/18 in the PRONOM database.
Currently, the Photographic Imaging, Microfilm and Textual Preservation Lab are using the PDF format for distribution purposes only.