What practice ensures that a digital file has not changed over time?

The practice that ensures a digital file has not changed over time is fixity checks. Fixity checks are processes that involve creating and verifying checksums or hash values of files. When a file is created, a checksum is generated, which serves as a unique digital fingerprint for that specific file. Over time, this checksum can be used to confirm the integrity of the file by comparing it to a new checksum calculated at a later date. If the two values match, it indicates that the file has not been altered, ensuring its authenticity and integrity.

This process is crucial for long-term digital preservation, as it helps archivists identify any unintended changes or potential corruption of files. In contrast, file conversion, data restoration, and backup procedures play essential roles in the management of digital files but do not specifically serve to verify ongoing integrity over time like fixity checks do. File conversion might change the format of a file, data restoration typically brings files back to a previous state, and backup procedures focus on creating copies of files for recovery rather than verifying their unchanged state.