/ˈlɑːɡɪŋ/
noun — "the art of making your software confess everything it just did."
Logging is the practice in information technology of recording events, messages, or state changes generated by software, applications, or systems. Logs provide a historical record of system activity, which can be used for debugging, auditing, monitoring, and analyzing system behavior. Effective logging is crucial for troubleshooting, detecting anomalies, and maintaining reliable IT operations.
Technically, Logging involves:
- Event recording — capturing system messages, errors, warnings, or informational events.
- Timestamping — ensuring each log entry has a precise time reference for sequence tracking.
- Log storage and management — organizing logs for easy retrieval, analysis, and long-term retention.
- Log levels — classifying messages by severity such as DEBUG, INFO, WARN, ERROR, or FATAL.
Examples of Logging include:
- Recording user login attempts and failures in a web application.
- Capturing exceptions and stack traces in a server application.
- Storing network device activity logs to monitor performance or detect intrusions.
Conceptually, Logging is about creating a transparent record of software and system activity. Logs serve as a diagnostic tool, a compliance record, and a feedback mechanism for IT teams to understand, maintain, and improve systems over time.
In practice, logging is implemented using logging frameworks, system daemons, or cloud services that provide centralized collection, filtering, and analysis to support monitoring, alerting, and troubleshooting.
See Monitoring, Debugging, Event Management, Anomaly Detection, Audit Trail.