A log file (or simply a log) is a structured or semi-structured digital record that captures system states and events. Logs are generated by virtually every component of an IT environment, including operating systems, applications, network devices, and security tools.
Log files give IT teams detailed visibility into system activity, allowing them to track performance, detect anomalies, and respond to operational or security issues in real time.
Although the specific content of a log file depends on its source and intended purpose, most log entries typically include the following elements:
- Timestamp – when the event occurred
- Source – the system or application that generated the event
- User or Process ID – who or what triggered the event
- Status Code – especially relevant for services like web servers or APIs
- Event Type or ID – a numeric or categorical identifier for the event
- IP Address / Hostname – common in access or connection-related logs
- Severity Level – the criticality of the event (e.g., info, warning, error)