====== CloudWatch Metrics ======

**What it is:** Time-series performance data (CPUUtilization, RequestCount, Latency, etc.).

**What it’s for:**
  * Observe system health over time.
  * Trigger alarms and auto scaling based on thresholds.

**Key ideas:**
  * Metrics can be AWS-provided or custom.
  * Commonly used for scaling decisions (ASG target tracking, alarms).

**Exam cues:**
  * “scale when CPU > 70%” → metrics + alarm/policy.

**Hard words:**
  * *time-series* /ˈtaɪm ˌsɪriːz/: chuỗi theo thời gian
  * *utilization* /ˌjuːtələˈzeɪʃn/: mức sử dụng
  * *threshold* /ˈθreʃhoʊld/: ngưỡng