VM scale sets are used for deploying multiple VMs at once without the need for manual actions or using scripts. You can then manage them all at once from a single place. VM scale sets are typically used to build large-scale infrastructures, where keeping all of your VMs in sync is key. The maintenance of VMs, including keeping them in sync, is handled by Azure. VM scale sets use Availability Sets under the hood. VMs inside a scale set are automatically spread over the fault and update domains by the underlying platform. VM scale sets use Azure autoscale by default. You can, however, add or remove instances yourself instead of using autoscale.
When creating a scale set, a couple of artifacts are created for you automatically. As well as the number of VMs you have specified being added to the set, Azure Load Balancer and Azure autoscale are added, along with a virtual network and a public IP address, as shown in the following screenshot:
