Auto Scaling and ELB

Elastic capacity behind one address.

An Auto Scaling group keeps between min and max identical instances running, launching new ones from a launch template when a policy (e.g. average CPU > 50 %) says so and removing them when load falls. An Application Load Balancer gives users one DNS name and spreads requests across the healthy instances, so capacity can change without users noticing.

This is the difference between scalable (can grow) and elastic (grows and shrinks automatically with demand).