A note on the source of much (most?) of the confusion about what cloud is and what the term means. I’m an etymology fan so this might only interest me, but I think it’s helpful.
I need to do some real research and provide examples, but originally “cloud” was a metaphor for a collection of computing and data resources that, unlike a cluster, was kept opaque in its details with an intentionally simplified API. So the resources were not presented to entities needing them with a well-defined architecture; instead they were presented as a hazy collection with only a few necessary characteristics. A cloud: unclear in shape and extent, but still “raining” when needed.
So the term was invented to describe what the resources look like. Now, though, it doesn’t mean this at all. Today “cloud” describes the way the resources are accessed. Big difference!
A better metaphorical term for cloud, if it were invented today, might be “concierge.” Never mind the details, just tell me what you need and how much, and provided you can pay for it, I’ll get it for you. Give me a nice tip and I’ll give you even better service next time …