TL;DR Single servers fail  – load balancers distribute traffic across multiple servers, enabling scalability, redundancy, and zero-downtime maintenance. Layer 4 (IP/port) is faster; Layer 7 (HTTP) enables content-based routing  using URLs, headers, or cookies. Externalize session storage  (Redis) instead of sticky sessions for true stateless scaling. Health checks enable automatic failover  – configure active probes with appropriate depth and intervals. Cloud managed LBs  (ALB, NLB, Google Cloud LB, Azure LB) reduce operational overhead. Single servers fail. They hit capacity limits. They require maintenance. They create single points of failure. Load balancing distributes traffic across multiple servers, enabling scalability, redundancy, and maintainability. For SaaS applications serving significant traffic, load balancing is essential infrastructure. Load Balancing Fundamentals Load balancers sit between clients and server pools.…