What is a load balancer?
Sits in front of a group of servers and spreads incoming requests across them.
One server can only handle so many users. So big apps run many copies of the same server. But then, who decides which copy gets your request?
What it is
A load balancer sits in front of a group of servers and spreads incoming requests across them.
How it works
Every request hits the load balancer first. It picks a server, maybe the next one in turn, or the one with the fewest connections, and forwards the request. It also runs health checks, and stops sending traffic to any server that stops responding.
Why it matters
You can add servers when traffic spikes, take one down for an update, or lose one entirely, and users never notice.
