.log files are text-based records automatically generated by software, systems, or devices to track events, errors, and activities. They function as a running journal, appending new entries over time. While individual entries are small, these files continuously grow as long as the associated software runs. Unlike configuration files or temporary data, log files are persistent and cumulative by design, meaning their size inherently increases unless managed.

For instance, web servers like Apache or Nginx create access and error logs recording every user visit and server issue. Similarly, complex applications such as databases (e.g., MySQL, PostgreSQL) generate logs for transactions, queries, and performance metrics. These logs are vital across IT, web hosting, and application management for monitoring health and troubleshooting problems.

While essential for diagnostics and security auditing, uncontrolled log files pose a risk: they can consume significant disk space, potentially leading to full disks that crash systems or stop applications. Implementing log rotation policies, where files are automatically archived, compressed, or deleted after reaching size or age limits, is the standard solution. Regularly reviewing log retention needs ensures valuable history is kept without wasting storage.