A request log is a record of API activity: which endpoint was called, when it happened, what identity or key was used, the source IP address, and sometimes the response status or error code. In practice, it gives defenders a timeline of how an application or service was accessed.
Request logs matter because stolen API keys, abused sessions, and automated attacks often leave traces in the pattern of calls they generate. Security teams use logs to spot unusual locations, spikes in traffic, repeated failures, data-enumeration behavior, or actions taken outside normal hours. In a payment or cloud environment, logs can also confirm whether a secret key was used after exposure, helping teams rotate credentials, revoke access, and limit damage. Good request logging is one of the fastest ways to turn an unknown compromise into a contained incident.