"What cannot be measured cannot be managed" — this maxim is brutally effective with cloud costs. In on-premises, buying more servers required approval; in cloud, one terraform apply by a developer creates tens of thousands of dollars monthly in minutes. In this distributed, real-time, self-service environment, cost control requires three layers: visibility (viewing) → budget (thresholds) → auto-response (control) — provided respectively by Cost Explorer, Budgets, and CUR + Budgets Action