Load Balancer overview

Distributes incoming network connections or HTTP requests across a pool of backend instances to maximize throughput, minimize latency, and ensure availability. Operates at Layer 4 (TCP/UDP) or Layer 7 (HTTP/HTTPS). L7 load balancers (AWS ALB, GCP HTTPS LB) support path-based and header- based routing, SSL termination, sticky sessions, health checks, and WebSocket upgrades. L4 load balancers (AWS NLB) offer lower latency for TCP-based protocols. Cloud-native load balancers integrate with auto-scaling groups to drain connections gracefully during deployments. Often co-located with a WAF or DDoS protection layer.