AWS CloudWatch is the eye of your AWS account. It collects monitoring and operational data in the form of logs, metrics, and events.
Metrics are time-series data (e.g., CPU %, Error Count). **Architect Hint:** Don't just watch CPU. Set up **CloudWatch Alarms** on business metrics, like 'Number of Failed Payments > 5 in 1 minute'. This allows you to catch business logic errors before they affect your bottom line.
Forget scrolling through megabytes of text logs. **Logs Insights** allows you to run SQL-like queries on your logs. "fields @timestamp, @message | filter @message like /Error/ | sort @timestamp desc". It's incredibly fast and powerful for production troubleshooting.
Q: "How do I save money on CloudWatch Logs?"
Architect Answer: "Set a **Retention Policy**. By default, CloudWatch keeps logs forever, which can become expensive. Set your Dev/Test logs to expire after 7 days and Prod logs to archive to S3 after 30-90 days. Also, avoid 'Log Spam' by using the appropriate log levels (Warning/Error) in production."