Glossary
Audit logging
Also: audit trail, security logging
Audit logging is recording security-relevant events, such as logins, privilege changes, and access to sensitive data, so they can be monitored and later investigated. You cannot detect or reconstruct what was never recorded, which is why frameworks treat logging as a foundational control.
In code
It is a log call on a sensitive action. It dies quietly in a diff when that call is deleted as 'noise', dropped below the production log level, or stripped of the actor so an event can no longer be attributed.