# Auto Scaling

* Normally if you have an app or system, it won't continually be under maximum load.<br>
* 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<br>
* &#x20;This is when ASG comes in; ASG automatically:\
  \&#xNAN;**- Scales out when there is an increased load.**\
  **- Scales in when there is a decreased load.**\
  **- It will also replace unhealthy targets/instances.**<br>
* **ASG and ELB work very well together** because ASG can provide the instances and ELB can distribute the load between all of them.