ANSWER: PDF/A is a standard that defines formats for long-term archiving of electronic documents. The PDF/A standard is based on Adobe's PDF format.

The PDF/A standard is ISO 19005.

The idea behind the PDF/A initiative was to provide a mechanism for representing electronic documents in a manner that preserves their visual appearance over time, independent of the tools and systems used for creating, storing, and rending the files.

Why do we need PDF/A?

Approved archiving formats vary from country to country. Traditional, hard-copy archiving methods (paper and microfilm/microfiche) guarantee reproducibility but are outdated for modern technology. Large documents cannot be sent around the globe quickly. Also, it is extremely difficult to search paper documents, microfilm documents, or microfiche documents for specific content.

In a first step toward electronic archiving, many organizations are now archiving documents in TIFF format. TIFF guarantees reproducibility in the long term and has an established structure. TIFF is also easy to transmit in a worldwide business environment.

Although moving from hard-copy format to the TIFF format is a step in the right direction when it comes to archiving documents, relying on the TIFF format has several disadvantages:

  • TIFF documents are not easily searchable.
  • Because TIFF is a raster format as opposed to a vector format, TIFF files are, in general, quite large.

  • TIFF files depend upon a specific raster resolution, whereas page content in a PDF document is usually resolution independent. The PDF format will therefore profit from technological advances in reproduction devices (printers, monitors, etc.) long into the future; that is not the case with the TIFF format.

  • Metadata such as title, author, creation date, modification date, subject, keywords, etc. can be stored in a PDF file, and PDF files can be automatically classified based on the metadata, without requiring human intervention.

What's in the PDF/A standard?

The PDF/A standard specifies the characteristics that a PDF file must have in order to meet the criteria that are set forth in the standard.

The standard classifies PDF/A as PDF/A-1 (Part 1) and PDF/A-2 (Part 2). PDF/A-1 is further divided into the conformance levels PDF/A-1a and PDF/A-1b.

Creating PDF/A files and verifying PDF/A compliance

Some applications can create PDF/A files, tell you whether or not an existing PDF file is a PDF/A file, or both.

See also What is PDF?