PDF/A Explained: Why Long-Term Archives Use a Stricter Kind of PDF

If you've ever submitted a thesis, a government record, or legal evidence, you may have been asked to submit it as "PDF/A" rather than a regular PDF. Both open identically today — the difference is in how strictly the file is built internally.

A regular PDF has a hidden long-term-preservation risk

A regular PDF is allowed to reference external resources — say, not embedding a particular font and instead relying on the opening computer having that font installed, or linking out to an external audio or video file. That works fine right now, but ten or twenty years from now that font might be long discontinued, or that external link might be dead, and the document could open garbled or missing content.

PDF/A's core idea: seal everything inside the file itself

PDF/A (Archival) adds several mandatory requirements on top of a regular PDF:

• Every font used must be fully embedded — no relying on system fonts.
• No dependence on externally linked audio/video or dynamic content like JavaScript.
• Color must be self-contained, not dependent on an external color profile.
• No encryption (to avoid the file becoming permanently unopenable if a password is lost).

In other words, PDF/A trades away some of the fancier capabilities (embedded video, for instance) in exchange for a guarantee: open it decades from now, and it looks exactly the same as it does today.

Where PDF/A is explicitly required

• Government document archival systems
• Evidence submissions to courts and law firms
• Digital preservation of academic theses at libraries and universities
• Financial or compliance documents a business needs to retain long-term (10+ years)

Does the average user need to care about PDF/A?

For everyday editing and sharing with colleagues, a regular PDF is entirely fine. You only need to specifically convert to or export as PDF/A when a submission explicitly requires it (usually spelled out in submission instructions). A tool like LocalPDF, focused on everyday editing (changing text, adding images, managing pages), exports a standard PDF — if your destination specifically requires PDF/A, run the edited file through a dedicated PDF/A conversion tool afterward.