What happens when a resource is reserved?

Since Azure Reservations first became available a few years ago, it has quickly become a fast and easy way for customers to save money, with a time commitment of up to 3 years of usage. Depending on the type of resource, its model, and the commitment duration, the discounts can go as high as 72% (for example, on a 3-year reservation of an M-sized virtual machine (VM)). This can significantly cut costs and represent the first quick win of any cost management governance process.

On the other hand, customers who have embraced the cloud paradigm of fluid and ever-changing resource consumptions are always a bit wary of committing to a specific resource for many months. When a resource is reserved, there is nothing static about it: it is simply a billing discount that is booked in advance with the condition of spending the amount of money that the reservation is entitled to.

Please note that in non-US countries, due to the exchange rate for...