What is the difference between migration and emulation for keeping digitized records readable over time?

Digitizing paper or analog records is only the first step. The harder, long-term challenge is keeping those digital files openable as software, file formats, and hardware become obsolete. Migration and emulation are the two main strategies for solving that problem, and many programs use both.

Migration

Migration means periodically moving records from aging formats or systems into current ones. As a format heads toward obsolescence, you convert the files to a newer, well-supported format so they remain openable with today’s tools.

• Focus: changing the record to fit current technology.
• Examples: converting older office documents to a current standard, or refreshing image formats to a widely supported successor.
• Strengths: files stay usable with mainstream, modern software; no special environment needed.
• Risks: each conversion can subtly alter formatting, structure, or embedded metadata, so you must verify that essential content and characteristics survive each move.

Emulation

Emulation means keeping the original files unchanged and instead recreating the environment needed to open them. Software mimics the old operating system or application so the original file behaves as it originally did.

• Focus: changing the environment, not the record.
• Examples: running a vintage application or operating system inside emulation software to open files in their native format.
• Strengths: preserves the original look, behavior, and interactivity, which matters for complex or executable content.
• Risks: requires maintaining or rebuilding emulators over time, and the experience can be harder for everyday users.

Choosing an approach

Neither approach is universally “better.” Migration tends to suit large volumes of common document and image formats where ongoing accessibility matters most. Emulation suits complex, interactive, or rendering-sensitive materials where exact behavior must be retained.

Sound preservation practice combines them with format choices that reduce risk in the first place: using open, well-documented formats, capturing strong descriptive and technical metadata, validating files after any change, and storing multiple copies. Recordkeeping standards and digitization guidelines stress that a digitized record only counts as preserved if it stays authentic, complete, and usable for as long as its retention period requires.

For related guidance, see the digitization and imaging hub.