What is cloud computing?

Having listened to Google, having done my reading I am still not clear on what cloud computing is for each of the companies offering it. I guess it depends on who you talk to and how they define the cloud and what cloud computing offering they have for you. Most of us Internet oldtimers remember that the Internet was the original cloud. It took care of things e.g. routing. But are all the cloud offering taken care of e.g. security? Privacy and security seem to be still at an immature state.

Now NIST has taken on the challenge of helping with the definition of "cloud computing" and has drafted a document. I guess the next step is to define a standard for cloud security or at least some common APIs.

Background material:
NIST Cloud computing

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