An activity log is a timestamped chronological record that documents operations, events, and user actions within an information system, application, or network infrastructure. Each log entry typically captures essential metadata including the precise time of the event, the identity of the user or automated process involved, the specific action taken (such as login attempts, file modifications, configuration changes, or data access), and contextual details like source IP addresses or affected system components.

Activity logs serve as a critical security control and are indispensable for establishing accountability, detecting potential security threats, and conducting forensic investigations. They provide organizations with a transparent and verifiable audit trail that enables proactive monitoring of system behavior, helps meet regulatory compliance requirements, and allows security teams to pinpoint the scope and timeline of security incidents. Proper management of activity logs—including secure storage, consistent review, and correlation across systems—is fundamental to maintaining a robust cybersecurity posture.