Load Balancer
System that distributes incoming traffic across multiple servers.
Definition
A load balancer is a system that distributes incoming network traffic across multiple servers to ensure no single server becomes overwhelmed. Load balancers enable horizontal scaling, improve reliability through redundancy, and can provide additional functions like SSL termination and health checking.
Modern load balancers operate at different layers—from simple round-robin distribution to sophisticated content-aware routing based on request characteristics.
Why It Matters
Single servers can't handle unlimited traffic and represent single points of failure. Load balancers enable scaling beyond single-server limits while improving reliability.
For operations teams, load balancer configuration directly impacts availability and performance.
Examples in Practice
A load balancer distributes traffic across ten web servers, enabling the application to handle 50x the traffic of a single server.
Health checks automatically remove unhealthy servers from the pool, maintaining availability despite server failures.
Load balancer routing sends API requests to a dedicated server pool optimized for API workloads.