What is the difference between migration and emulation in digital preservation, and when should you use each?

Digital records do not survive on their own. File formats fall out of use, software is retired, and hardware fails. Migration and emulation are the two main strategies for keeping digital content usable over time. They solve the same problem from opposite directions.

What Is Migration?

Migration moves content forward by changing the records themselves. You periodically convert files from aging or obsolete formats into current, well-supported ones, then access the new versions with today’s software.

For example, a document in an outdated word-processing format might be converted to a current open standard, or an image saved in a proprietary format might be re-saved in a widely supported one.

Migration keeps the content readable on modern systems, but each conversion carries a small risk of altering formatting, metadata, or embedded features.

What Is Emulation?

Emulation leaves the original files unchanged. Instead, it recreates the original computing environment, the old operating system, application, or hardware behavior, on current machines so the record opens and behaves the way it originally did.

This is valuable when the exact look, behavior, or interactivity matters and cannot be reproduced by simply converting the file. The trade-off is technical complexity and the ongoing effort of maintaining or building emulation environments.

When to Use Each

Choose migration when:

• The content is mostly informational (text, tabular data, standard images).
• Open, well-documented target formats exist.
• You want broad, low-friction access on everyday tools.

Choose emulation when:

• Original behavior, appearance, or interactivity is essential (software, complex documents, multimedia, dynamic records).
• Conversion would lose meaning or authenticity.
• The format is too complex or proprietary to migrate safely.

In practice, programs often use both, migrating routine records while preserving original environments for high-value or complex materials. Whichever you choose, document your decisions, verify that records remain authentic and complete after any process, and revisit the plan as technology changes.

For related guidance, see the archives and preservation hub. Recognized standards for managing records in digital environments reinforce the same goal: keeping records accessible, authentic, and usable for as long as they are needed.