What is the cloud? Among all the possible definitions, one captures the essence of the cloud in the simplest way: “The cloud is a huge pool of resources that supports a variety of services.”
The foundation of the cloud is a large pool of storage, compute, and networking resources. A key value proposition of the cloud is that you can acquire any amount of these resources at any time, from anywhere, without needing to worry about managing any underlying infrastructures. And when you are done with these resources, you can return them to the cloud just as easily to avoid the unnecessary cost to keep them around.
Important: Have you read page page xviii?
It contains valuable information ...