Logging is one of the most important techniques for understanding what an application does at runtime. When an error occurs or a performance problem appears, log records help developers diagnose the issue.

ASP.NET Core includes a built-in logging infrastructure, but Serilog provides a more flexible and powerful approach. It supports structured logging, which means log entries can contain searchable properties instead of only plain text.

Log levels should be selected carefully. Information is useful for normal application flow, Warning for possible issues, Error for real failures and Fatal for critical problems that may stop the application.

The log destination is also important. Console logging may be enough during development, while production systems often use files, databases, Elasticsearch or centralized logging platforms. Rolling files can help keep log size under control.

A good logging strategy improves debugging and observability. However, sensitive user data, passwords and tokens should never be written to logs. Logging is powerful, but it must be handled responsibly.