Auto Scaling

• Normally if you have an app or system, it won't continually be under maximum load.

• So if you're underestimating or overestimating your load, then there could be problems with cost and also, availability for customers/users, e.g. they might not be able to access the website because there might be a lot of latency because of too many users on the platform

• This is when ASG comes in; ASG automatically: - Scales out when there is an increased load. - Scales in when there is a decreased load. - It will also replace unhealthy targets/instances.

• ASG and ELB work very well together because ASG can provide the instances and ELB can distribute the load between all of them.