The Horizontal Pod Autoscaler (HPA) automatically scales Pod replicas based on observed metrics. It monitors CPU utilization, memory usage, or custom metrics via the metrics-server. The minReplicas and maxReplicas fields set scaling bounds. targetCPUUtilizationPercentage triggers scaling when average CPU crosses the threshold. HPA v2 supports multiple metrics and custom metrics from Prometheus. The behavior field controls scale-up and scale-down rates to prevent flapping. Vertical Pod Autoscaler (VPA) adjusts resource requests and limits automatically. Pod Disruption Budgets (PDB) ensure minimum availability during voluntary disruptions. Resource quotas limit namespace-level resource consumption. LimitRanges set default and max resources per container.