In the cloud, resources are allocated and deallocated on the fly — servers are constantly being started and stopped or replaced with other instances. The cloud

In the cloud, resources are allocated and deallocated on the fly — servers are constantly being started and stopped or replaced with other instances. The cloud provider does not know in advance when a resource will be requested or released. This introduces a delay between the moment a cost is incurred and the moment it is billed. This delay can be of several hours or even days, depending on the billing frequency (hourly, daily, monthly). For example: - You start an instance at 10am. You are billed for it from 10am to 11am. You stop the instance at 11:05am. The charge should be removed from the bill at 12pm (because bills are generated hourly). If you look at your bill at 11:05am though, you will still see a charge for an hour of usage, since your bill has not been updated yet. If you want to check if your charges were correctly applied to your bill, you will have to wait until 12pm to look at your bill again. Because of this delay, cloud providers cannot show your consumption / cost in real time: they would either show incorrect information (if they use billing data) or make you wait until they have updated their bills (if they use raw usage data).