Preemptible instances only differ from regular ones in that they are subject to be terminated by a incoming request for provision of a normal instance. If bidding is in place, this special type of instance could also be stopped by a higher priority preemptible instance (higher bid). Not all the applications are suitable for preemptible executions, only fault-tolerant ones can withstand this type of execution. On the other side they are highly affordable VMs that allow providers to optimize the usage of their available computing resources (i.e. backfilling).