PDF/A and long-term archiving

PDF/A is a restricted version of PDF designed for archiving — files that must remain openable and identical decades from now, long after today's software is gone. It's an ISO standard (ISO 19005) used widely by governments, courts, and libraries.

How PDF/A differs from a normal PDF

PDF/A is "PDF with the risky bits removed." To guarantee a file is self-contained and future-proof, it requires some things and forbids others:

• All fonts must be embedded — nothing may rely on the reader's system. (See font embedding.)
• No encryption — an archived file must open without a password.
• No external references — no linked audio, video, or web content that could rot.
• Colour must be device-independent, so it looks right on any future display.

The flavours

There are levels — PDF/A-1, A-2, A-3 — and conformance classes like "b" (basic, visual reproduction) and "a" (accessible, with tagged structure). Higher numbers allow more features, such as embedded files in A-3.

When you actually need it

If you're submitting to a court, archiving official records, or meeting a compliance mandate, PDF/A may be required. For everyday sharing, a normal PDF is fine. Converting to strict PDF/A usually needs dedicated archival software, but the principles — embed everything, avoid encryption — are good habits for any document you want to last.