File Integrity Monitoring System, is an IT security process and technology that tests and checks operating system (OS), database, and application software files to determine whether or not they have been tampered with or corrupted. FIM, which is a type of change auditing, verifies and validates these files by comparing the latest versions of them to a known, trusted “baseline.” If FIM detects that files have been altered, updated, or compromised, FIM can generate alerts to ensure further investigation, and if necessary, remediation, takes place. File integrity monitoring encompasses both reactive auditing as well as proactive, rules-based active monitoring.