Operational logs are the records systems generate while they run. They can capture login events, file access, application errors, API calls, job status, configuration changes, and other workflow details. In practice, they show what happened, when it happened, and which account or service did it.
They matter in cyber security because logs are both a defense tool and a source of risk. Defenders use them to detect suspicious behavior, trace an intrusion, confirm whether an alert is real, and reconstruct an attack path. At the same time, logs can expose internal processes, system names, service accounts, partner identifiers, and error messages that help attackers map a network or plan extortion. For that reason, organizations should restrict access, centralize and protect log storage, and avoid logging secrets or unnecessary operational detail.