You've learned how load balancers distribute traffic and maintain availability.
Distribution methods: Round-robin for simplicity, least connections for variable workloads, IP hash for client consistency. Layer balances fast but blind. Layer balances smart but slower.
Reliability features: Health checks detect failures. Failover redirects traffic. Connection draining enables graceful updates.
Implementation options: HAProxy and NGINX for flexibility. AWS ALB/NLB for managed convenience. Hardware appliances for dedicated performance.
Next, you'll see how these pieces fit into broader system design patterns.