load balancer
a device that spreads incoming traffic across several servers
Busy websites and apps run on several servers at once. A load balancer sits in front of them, takes each incoming request and passes it to a server with spare capacity. If one server fails, it stops sending traffic there. Because every request passes through it, it sees and can change all of that traffic.
Think of it as
A host at a busy restaurant who seats each new guest at whichever table has a free waiter.
Ideas that use this term