Anomalous activity is behavior that differs from an expected baseline for a device, user, application, or network. A deviation is not automatically malicious: a new connection may result from approved maintenance, a changed workload, or normal operational variation. Baselines and asset context help analysts decide whether a difference needs attention.
In cyber security, anomalies can reveal compromised accounts, unauthorized software, unusual communications, or changes to industrial systems. Defenders use monitoring tools to flag deviations, then investigate supporting evidence such as asset roles, endpoint data, network records, and maintenance schedules. Risk scores can help prioritize review, but their value depends on accurate, current data and understandable reasoning; they support investigation rather than proving that an event is malicious or that a system meets a compliance requirement.