What is cloud computing
In general, cloud computing customers do not own the physical infrastructure,
instead avoiding capital expenditure by renting usage from a third-party provider.
They consume resources as a service and pay only for resources that they use.
Many cloud-computing offerings employ the utility computing model, which is analogous to how traditional utility services (such as electricity) are consumed.
Sharing "perishable and intangible" computing power among multiple tenants can improve utilization rates,
as servers are not unnecessarily left idle (which can reduce costs significantly while increasing the speed of application development).