.log File — Log File

LOG files contain chronological records of events, errors, transactions, or status messages generated by software applications, operating systems, web servers, and hardware devices. Log files are essential for system administration, debugging, security auditing, and performance monitoring. They typically contain timestamped entries with severity levels (DEBUG, INFO, WARN, ERROR, FATAL), source identifiers, and human-readable messages. Common log formats include the Apache Combined Log Format for web servers, syslog format for Unix systems, and JSON-structured logging used by modern applications. Log files can grow continuously as systems run and often require rotation policies (logrotate on Linux) to manage disk space. Analysis tools like grep, awk, Elasticsearch/Logstash/Kibana (ELK stack), Splunk, and Grafana Loki are commonly used to search, filter, and visualize log data. Security-focused log analysis is critical for intrusion detection, compliance auditing, and forensic investigations. Centralized logging systems aggregate logs from multiple sources for unified monitoring.